Heat actuated and projected lithography systems and methods

ABSTRACT

In accordance with an embodiment of the disclosure, a tip array can include an elastomeric tip substrate layer comprising a first surface and an oppositely disposed second surface, the tip substrate layer being formed from an elastomeric material; a plurality of tips fixed to the first surface, the tips each comprising a tip end disposed opposite the first surface, the tips having a radius of curvature of less than about 1 micron; and an array of heaters disposed on the second surface of the tip substrate layer and configured such that when the tip substrate layer is heated by a heater, a tip disposed in a location of a heated portion of tip substrate layer is lowered relative to a tip disposed in a location of an unheated portion of the tip substrate layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Application Ser. Nos.61/719,907, filed Oct. 29, 2012, entitled “Heat Actuated and ProjectedLithography Systems and Methods” and 61/719,918, filed Oct. 29, 2012,entitled “Heat Actuated and Projected Lithography Systems and Methods”,which are hereby incorporated by reference in their entirety.

BACKGROUND

The demand for nanoscale components in integrated circuits, medicaldiagnostics, and optoelectronics has generated much interest in thedevelopment and study of various lithography strategies. Conventionalpatterning methods, however, have failed to satisfy the need for rapidlypatterning of nanoscale features at a low cost. The expense ofpatterning equipment grows dramatically as the required resolutionincreases.

With conventional far-field optical lithography, lateral featureresolution is diffraction-limited, as defined by the Rayleigh or Abbéconditions, which in practical terms only allow feature dimensions ofapproximately half the incident wavelength. In order to overcome thediffraction limit, a number of lithography approaches have beenreported, including multi-photon induced photoresist polymerization,zone-plate array lithography, and phase-shift photolithography. Thoughthese techniques are highly parallel, they rely on non-standard opticalinstrumentation and light sources not readily available to mostresearchers, or they preclude arbitrary nanoscale pattern formation. Inorder to produce complex patterns, established approaches includingelectron-beam lithography, focused ion beam (FIB) lithography, andscanning probe microscopy (SPM)-based techniques such as dip-pennanolithography (DPN) have been employed. Near-field scanning opticalmicroscopy (NSOM)-based techniques and scanning near-fieldphotolithography (SNP) are promising custom lithographic methods forsub-diffraction limit patterning, but are inherently low throughput andrestricted to scan areas several hundred microns in length.

In order to generate sub-diffraction limit features, SNP optics rely onthe evanescent field of incident light passing through an aperture, theintensity of which is strongly dependent on the distance between thisaperture and the surface. To control precise aperture heights andlateral registry, SNP relies on feedback systems used inpiezo-controlled SPM instruments. Though highly parallel two-dimensional(2D) silicon-based NSOM aperture arrays have been fabricated, aligning alarge area substrate surface with near-field proximity to this hard,non-deformable aperture array remains challenging. As a result, nosuccessful demonstrations of their use in homogeneous patterning havebeen reported.

Beam pen lithography (BPL) is another desktop fabrication technique,which uses light to write patterns, as opposed to electrons and otherparticle-based techniques. Near-field apertures in a BPL tip array offera direct route to circumvent the diffraction limit present inconventional photolithography. However, BPL is limited in that all tipsin the array act in unison, making this technique only useful forgenerating replicas of patterns, and the apertures are eitherconstructed serially using a focused ion beam or in parallel using amechanical stripping technique that yields large micron-sized pores.

SUMMARY

In accordance with an embodiment of the disclosure, a method ofpatterning can include dividing an image into a set of frame sections;determining a tip pattern for a respective portion of an image to bepatterned by each tip of the tip array in each frame section of the setof frame sections; disposing the tip array in a patterning position in afirst location of the substrate corresponding to a location of thesubstrate in which the first frame section in the set of frame sectionsis to be patterned; projecting a first pattern of radiation onto the tiparray to selectively irradiate one or more tips of the tip array andpattern the substrate, wherein the first pattern of radiationcorresponds to a tip pattern for the first frame section; disposing thetip array in a patterning position in a second location of the substratecorresponding to a location of the substrate in which the second framesection in the set of frame sections is to be patterned; projecting asecond pattern of radiation onto the tip array to selectively irradiatetips of the tip array and pattern the substrate, wherein the secondpattern of radiation corresponds to a tip pattern for the second framesection; and repeating the disposing and projecting for each framesection in the set of frame sections to pattern the image.

In accordance with another embodiment of the disclosure, a method forpatterning a substrate using projected radiation can include (a)subdividing an image to be patterned into frame sections, wherein eachframe section corresponds to a portion of the image to be patterned on asubstrate by each pen of a tip array in a patterning location; (b)receiving a set of data inputs, the set of data inputs comprising aspatial size of the image, a center location of the image, rotationaloffset of the image, a delay time, an exposure time, and a safety time;(c) outputting an instruction data set based the set of data inputs; (d)receiving with a control system for the tip array the instruction dataset for directing movement of the tip array to a patterning location;(e) disposing the tip array in a patterning position in a firstpatterning location; (f) detecting a Z-piezo voltage, wherein athreshold voltage corresponds to the tip array being in a patterningposition; (g) projecting onto the tip array a first pattern of radiationafter detecting the threshold voltage; the first irradiation patternselectively irradiate the tip array to pattern a first portion of theimage corresponding to a first subset of the frames sections located inthe first patterning location; (h) maintaining projection of the firstpattern of radiation for an exposure time; (i) maintaining the tips inthe patterning position for a hold time equal to the exposure time, thedelay time, and the safety time to pattern the first portion of theimage on the substrate; (j) stopping projection of the first pattern ofradiation after the exposure time has lapsed; (k) removing the tips fromthe patterning position after the hold time has lapsed; (l) moving thetips to a second patterning location once the tips are removed from thepatterning position, the spatial location of second patterning locationbeing provided by the instruction data set; and, (m) repeating steps(e)-(k) at the second patterning location to pattern the substrate in asecond patterning location.

In accordance with an embodiment of the disclosure, a method of aligninga tip array and pattern of radiation projected from a projector caninclude positioning a projector comprising a digital micromirror deviceand a macro lens a distance from a tip array, the distance beingsubstantially equal to the focal length of the macro lens; aligning thedigital micromirror device, the macro lens and a beam splitter using anoptical breadboard; displaying a first test pattern of radiation fromthe projector and projecting the first test pattern onto the tip array,wherein the first test pattern has first ratio of L/N, wherein L is thenumber of mirrors disposed on an edge of an illuminated portion of thetest pattern and N is the number of tips disposed on an edge of anilluminated portion of the test pattern; observing the projected testpattern projected on a back surface of the tip array; adjusting theposition of the digital micromirror device to center the first testpattern on the tips disposed in the irradiate portion of the first testpattern; adjusting the position of the beam splitter until the testpattern is in rough focus on the tip array; adjusting the focal lengthof the macro lens until the test pattern is in sharp focus; projecting asecond test pattern of radiation onto the tip array, wherein the secondtest pattern has a second ratio of L/N that is smaller than the firstratio of L/N; adjusting the size, orientation, and position of thesecond test pattern such that the projected second test patternsubstantially matches the tips in the array until one tip of the tiparray is in the center of each irradiated portion of the second testpattern.

In accordance with an embodiment of the disclosure, a system forpatterning a substrate using projected radiation, the system including atip array coupled to an actuator comprising a piezo driver; a projectorincluding a radiation source; a substrate stage; a control modulecommunicatively linked to the microscope and the projector, the moduleincluding a processor for executing instructions stored on a memory, theinstructions to: (a) subdivide an image to be patterned into squareframe sections, wherein each square frame section corresponds to aportion of the image to be patterned on a substrate by each pen of a tiparray in a patterning location; (b) receive a set of data inputs, theset of data inputs comprising a spatial size of the image, a centerlocation of the image, rotational offset of the image, a delay time, anexposure time, and a safety time; (c) generate an instruction data setbased the set of data inputs, the instruction set for directing movementof the tip array to a patterning location by the actuator; (d) detect athreshold piezo voltage corresponding to the tip array being in apatterning position; (e) cause the projector to: project a firstirradiation pattern onto the tip array after detecting the thresholdvoltage, wherein the first irradiation pattern corresponds to a firstportion of the image and the first portion of the image corresponds to afirst subset of the frames sections located in the first patterninglocation, maintain projection of the first irradiation pattern for anexposure time, and stop projection of the first pattern of radiationafter the exposure time has lapsed; (f) cause the actuator and/orsubstrate stage to: maintain the tips in the patterning position for ahold time equal to the exposure time, the delay time, and the safetytime to pattern the first portion of the image on the substrate, removethe tips from the patterning position after the hold time has lapsed,and move the tips to a second patterning location once the tips areremoved from the patterning position, the spatial location of secondpatterning location being provided by the instruction data set; and (h)repeat steps (e) and (f) at the second patterning location to patternthe substrate in a second patterning location.

In accordance with another embodiment of the disclosure, a system forpatterning a substrate using projected radiation can include a micro tiparray coupled to an actuator; a projector including a radiation source;a substrate stage; a control module communicatively linked to theactuator, optionally the substrate stage, and the projector, the moduleincluding a processor for executing instructions stored on a memory, theinstructions to: divide an image to be patterned into a set of framesections; determine a tip pattern for a respective portion of an imageto be patterned by each tip of the tip array in each frame section ofthe set of frame sections; and for each frame section in the set offrame sections, cause the actuator and/or the substrate stage to disposethe tip array in a patterning position in a first location of asubstrate corresponding to a location of the substrate in which thefirst frame section in the set of frame sections is to be patterned;cause the projector to project a first pattern of radiation onto the tiparray to selectively irradiate one or more tips of the tip array andpattern the substrate, wherein the first pattern of radiationcorresponds to a tip pattern for the first frame section; cause theactuator and/or the substrate stage to dispose the tip array in apatterning position in a second location of the substrate correspondingto a location of the substrate in which the second frame section in theset of frame sections is to be patterned; and cause the projector toproject a second pattern of radiation onto the tip array to selectivelyirradiate tips of the tip array and pattern the substrate, wherein thesecond pattern of radiation corresponds to a tip pattern for the secondframe section.

In accordance with an embodiment of the disclosure, a tip array caninclude an elastomeric tip substrate layer comprising a first surfaceand an oppositely disposed second surface, the tip substrate layer beingformed from an elastomeric material; a plurality of tips fixed to thefirst surface, the tips each comprising a tip end disposed opposite thefirst surface, the tips having a radius of curvature of less than about1 micron; and an array of heaters disposed on the second surface of thetip substrate layer and configured such that when the tip substratelayer is heated by a heater, a tip disposed in a location of a heatedportion of tip substrate layer is lowered relative to a tip disposed ina location of an unheated portion of the tip substrate layer.

In accordance with an embodiment of the disclosure, a method of aligninga tip array and pattern of radiation projected from a projector caninclude positioning a projector comprising a digital micromirror deviceand a macro lens a distance from a tip array, the distance beingsubstantially equal to the focal length of the macro lens; aligning thedigital micromirror device, the macro lens and a beam splitter using anoptical breadboard; displaying a first test pattern of radiation fromthe projector and projecting the first test pattern onto the tip array,wherein the first test pattern has first ratio of L/N, such that Nnumber of tips is disposed in an irradiated portion of the test pattern;observing the projected test pattern projected on a back surface of thetip array; adjusting the position of the digital micromirror device tocenter the first test pattern on the tips disposed in the irradiateportion of the first test pattern; adjusting the position of the beamsplitter until the test pattern is in rough focus on the tip array;adjusting the focal length of the macro lens until the test pattern isin sharp focus; projecting a second test pattern of radiation onto thetip array, wherein the second test pattern has a second ratio of L/Nthat is smaller than the first ratio of L/N; adjusting the size,orientation, and position of the second test pattern such that theprojected second test pattern substantially matches the tips in thearray until one tip of the tip array is in the center of each irradiatedportion of the second test pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a high-level illustration of one embodiment of a lithographysystem according to the disclosure herein;

FIG. 1B is a schematic illustration of a projected lithography systemusing a beam pen tip array according to the disclosure herein;

FIG. 2A is a user interface for computer-implemented alignment of alithography system according to the disclosure herein;

FIGS. 2B-2D are flowcharts for methods to complete an alignment processfor a lithography system according to the disclosure herein;

FIG. 2E is an optical image illustrating the checkerboard alignmentprocess in accordance with an embodiment of the disclosure herein;

FIG. 3 is a user interface for controlling a lithography process usingthe system of FIG. 1;

FIG. 4 is a flowchart for a method of completing a lithography processaccording to the disclosure herein;

FIG. 5 is a high-level illustration of another embodiment of alithography system according to the disclosure herein;

FIG. 6 is a high-level illustration of still another embodiment of alithography system according to the disclosure herein;

FIG. 7 is a user interface for controlling a lithography process usingthe system of FIG. 5 or FIG. 6;

FIGS. 8A-8D are flowcharts for further methods to complete a lithographyprocess according to the disclosure herein;

FIG. 9 is a high-level block diagram of a computing system according tothe disclosure herein;

FIG. 10A is a schematic illustration of thermal actuation of a tip arrayin accordance with an embodiment of the disclosure herein;

FIG. 10B is a simulation of the heat profile in a PDMS and glasssubstrate according to the disclosure herein;

FIG. 10C is an SEM image of a micro-heater array with a close up of asingle coil according to the disclosure herein;

FIG. 10D is an SEM image of a 4×4 tip array fabricated on top of microcoil heaters according to the disclosure herein;

FIG. 11 is a schematic illustration of a fabrication process of athermal actuation tip array in accordance with an embodiment of thedisclosure herein;

FIG. 12A is a thermal image of one heater in an array in an “off” and an“on” state according to the disclosure herein;

FIG. 12B is a graph illustrating the measurement of the actuation andextraction of a timescale τ and amplitude A according to the disclosureherein;

FIG. 12C is a graph illustrating the linear relationship observedbetween applied power and actuation amplitude according to thedisclosure herein;

FIG. 12D is a graph of an amplitude profile along the surface of thePDMS according to the disclosure herein, showing minimal crosstalk andfatigue;

FIG. 13A is a schematic of using multiple tips to write a continuouspattern across a substrate according to the disclosure herein;

FIG. 13B is a schematic of using several tips inked with different inkshaving different colors to generate multiple patterns on a substrateaccording to the disclosure herein, wherein continuations of the unitcell patterns result in every spot on the substrate being addressable byevery color;

FIG. 14A is a schematic illustration of a patterning method inaccordance with an embodiment of the disclosure herein;

FIG. 14B is an SEM image of patterns achieved by 13 tips of a 4×4 tiparray writing MHA on gold followed by chemical etching using a method ofpatterning with thermal actuation of the tips of the tip array accordingto the disclosure herein, wherein each box represents a patternedwritten by a single tip;

FIG. 15A is a schematic of an electrically addressable heater schemeaccording to the disclosure herein, wherein when electricity is allowedto flow by an external switch (here an NPN transistor), it heats aresistive coil pattern;

FIG. 15B is a schematic of a photo-selected heater scheme according tothe disclosure herein, wherein when the photoconductive discs areexposed to an irradiation source (e.g., light), electricity is allowedto flow which heats the photoconductor and actuates the tip;

FIG. 16A is a schematic illustration of a Polymer Pen Lithography setup;

FIG. 16B is a photograph of a 11 million tip array;

FIG. 16C is a scanning electron microscopy (SEM) image of the polymertip array of FIG. 16B;

FIG. 17 is a schematic illustration of a polymer tip array fabrication;

FIG. 18 is a graph illustrating feature size as a function of relativez-piezo extension, demonstrating the pressure dependence of feature sizewhen patterning with polymer pen or gel pen or beam pen lithography;

FIG. 19 is a schematic illustration of a beam tip array and a beam penlithography method;

FIG. 20 is an SEM image of a beam pen tip array, with the inset showingan aperture formed in a tip end;

FIGS. 21A and 21B are schematic illustrations of methods of making abeam pen tip array;

FIG. 22A is a schematic illustration of a hard tip soft springlithography tip array;

FIG. 22B is a schematic illustration of a method of making a hard tipsoft spring lithography tip array;

FIGS. 23A is an SEM image of Si tip array after KOH etching (40 wt %,75° C. for 65 min) with isopropyl alcohol, wherein Si substrate attacheddirectly to PDMS without SiO₂ passivation layer resulted in Si tipsfalling from PDMS surface during etching; the welling of PDMS insolution at relatively high temperatures may cause the interfacialstress that weakens the adhesion of Si to PDMS; employing a SiO₂passivation layer was found to significantly improve the stability of Sipen on a surface during etching;

FIG. 23B-23D show magnified images of different regions of 23 a;

FIG. 23E-23I show fabricated Si tip arrays on SiO₂/PDMS/glass: E, Siwafer (2×2 cm) on a cured PDMS surface on a glass slide before etchingand F, an actual tip array after etching in KOH. G, a SEM image of theSi tip array on SiO₂/PDMS/glass with 160 μm in pitch that are uniformwith bottom width 30±0.6 μm corresponding to about 47±0.9 μm in penheight; the pen height may vary up to 10% in optimized condition, sincethe original wafer itself used as a starting material in this experimenthas a variation of 10% in thickness; the inset shows the array in alarge area that shows the homogeneity of the tips; H, (311) planes wereintroduced during the wet etching with <110> oriented masks on a (100)Si surface. The measured surface intersection angles, α₁ and α₂, asdefined in this figure were 126.9° and 143.1° that correspond to the tipdefining planes of (311); rotation of the intersection of planes to<100>, φ, was 18.4°, and also showed that the tip plane is (311); I, thetip radius of curvature was 22±3 nm.

FIGS. 24A and 24B are schematic illustrations of a hard tip soft springlithography tip array coated with a graphene film;

FIG. 25A is a schematic illustration of a method of coating a graphenefilm on a tip array;

FIG. 25B is photographs of the method of FIG. 25a , illustrating (leftphotograph) PMMA/graphene film floating on water before coating, and(right photograph) submersion of the tip array in the fluid at an angleto coat the tips with the PMMA/graphene film;

FIG. 25C is a photograph of PMMA/graphene separated from the Nisubstrate by removing the Ni layer in an aqueous 1 M FeCl₃ solution;

FIG. 26A is a schematic illustration of a method of making a beam pentip array tip array using a lift-off procedure, the inset is an SEMimage of an aperture formed by the method;

FIG. 26B is a schematic illustration of a method of making a beam pentip array using a dry and wet etching process, the inset is an SEM imageof an aperture formed by the method;

FIG. 27A is an SEM image of a dot pattern formed using projectedlithography according to the disclosure herein using a beam pen tiparray;

FIG. 27B is graph illustrating the relationship between feature size andexposure time for a method of patterning using projected lithographywith a beam pen tip array according to the disclosure herein;

FIG. 27C is an SEM image of a line pattern formed using projectedlithography using a beam pen tip array according to the disclosureherein;

FIG. 28 is an SEM image of a pattern formed by projected lithographyaccording to the disclosure herein; the pattern was formed using 10,000coordinated tips addressing 10,000 points each creating a cm² image; thepattern includes mm-scale structures composed of micron-scale imageswith 300 nm dots

FIG. 29A is an SEM image of a serpentine resistor formed by projectedlithography with a beam pen tip array according to the disclosureherein;

FIG. 29B is an SEM image of resistors, planar capacitors, inductors, andsurface acoustic wave sensors formed by projected lithography with abeam pen tip array according to the disclosure herein;

FIG. 29C is a graph illustrating the sheet resistance of the resistorsof FIG. 29A;

FIGS. 30A and 30B are SEM image of dispersed semiconductor nanowireselectrically connected by leads that were formed by projectedlithography with a beam pen tip array according to the disclosureherein;

FIG. 31 is an SEM image of a pattern formed by projected lithographyaccording to the disclosure herein; the pattern is the phrase “HelloWorld” written in sixty-four languages with patterns comprised of 1 μmdots; and

FIG. 32 is a schematic illustration of conventional beam pen lithographypatterning.

DETAILED DESCRIPTION

Projected Lithography, for example projected beam pen lithography (pBPL)or projected lithography using heat actuable tip arrays, can allow forrapid patterning of sub-100 nm features in arbitrary arrangements acrossa cm-scale surface. With pBPL, small features are generated by directinglight through small apertures at the apexes of pyramidal tips of a beampen tip array. With projected lithography using heat actuable tipsarrays, light can be used to activate heaters disposed in proximity totips to selectively bring tips of the array into contact with asubstrate for patterning, or selective inking of the tips of the arrayprior to patterning.

Projected lithography utilizes large tip arrays which can be used togenerate large scale, complete images comprising small features byprojecting a series of frames of the image onto the tip array as itscans across the surface. For example, projected lithography canadvantageously allow for large-scale images to be generated by rasterscanning the tip array across a substrate and projecting and rapidlychanging the frames projected on the tip array as it raster scans. Thisallows each point on the substrate to be addressed by the tip array asit scans across the surface. Patterning using projected lithography canalso advantageously allow for patterning with variable exposure times(e.g., in grayscale) in which each pen is capable of writing differentsized features.

As compared to conventional BPL and other lithography methods, projectedlithography can allow for the patterning of a macro-pattern comprised ofmicro-patterns without the need to mask the entire tip array in thedesired macro-pattern or manipulate the tip array and/or the substratein the desired micro-pattern. For example, referring to FIG. 32, withconventional BPL a macro-pattern in the shape of an “N” or a “U” can beformed with micro-patterns of “U” by masking the tip array such that thetips are arranged in the “N” or “U” macro-pattern are selectivelyilluminated and then manipulating the tip array or the substrate in the“U” micro-pattern shape to generate the macro-pattern. Such masking andmanipulation of the tip array can be difficult with large macro-patternsand complex micro- or macro-patterns. In contrast, projected lithographyallows a base pattern comprising both the macro- and the micro patternsto be subdivided into patterning frames and the tips to be selectivelyilluminated with an irradiation pattern corresponding to the patterningframe, to pattern each frame of the base pattern while the tip arrayscans across the substrate. For example, projected lithography can allowfor generation of complex patterns while the tip array performs a simpleraster scan across the substrate surface. Projection of the irradiationpatterns corresponding to patterning frames can be rapidly changed asthe tip array is scanned across the substrate to generate large, complexpatterns rapidly and without complex manipulation of the tip array. Thisadvantageously eliminates the need to manipulate the tip array and/orthe substrate in complex patterns or perform complex masking of the tipsin the form of the complete image of the macro-pattern.

In one embodiment, a method for patterning using projected lithographycan include dividing an image into a set of frame sections anddetermining a tip irradiation pattern for a respective portion of animage to be patterned by selected tips of the tip array in each framesection of the set of frame sections. The tip array can be positioned ina patterning position in a first location of the substrate correspondingto the location of the substrate in which a first frame section in theset of frame sections is to be patterned. The first frame section ispatterned by projecting a first pattern of radiation onto the tip arrayto selectively irradiate one or more tips of the tip array and patternthe substrate. The first pattern of radiation corresponds to a tipirradiation pattern for the first frame section. The method can furtherinclude disposing the tip array in a patterning position in a secondlocation of the substrate corresponding to a location of the substratein which the second frame section in the set of frame sections is to bepatterned. The second frame section can be patterned by projecting asecond pattern of radiation onto the tip array to selectively irradiatetips of the tip array and pattern the substrate, wherein the secondpattern of radiation corresponds to a tip irradiation pattern for thesecond frame section. The positioning and projecting steps can berepeated for each frame section in the set of frame sections. The tiparray can be positioned in the patterning location by moving the tiparray and holding the substrate still, moving the substrate and holdingthe tip array still, or by moving both the tip array and the substrate.

In one embodiment of the disclosure, a system for projected lithographyincludes a tip array and a projector for projecting an irradiationpattern onto the tip array to selectively illuminate (e.g., irradiate)and/or actuate one or more tips of the tip array. The projector can becommunicatively coupled to a computer device for manipulating theirradiation pattern projected onto the tip array based on the spatiallocation of the tip array and the portion of the image to patterned inthat spatial location.

FIG. 1A illustrates an embodiment of projected lithography andspecifically pBPL. As shown in FIG. 1A, pBPL includes an array of tipshaving near-field apertures that are each individually addressed by alight source. For example, collimated light from a light source, such asa UV light emitting diode (LED) can be spatially modulated bymicromirrors of a digital micromirror device (DMD) and directed onto theback of the tip array in registry with the tips. The light addressingeach of the tips can be modulated by tilting the mirrors in the DMDdirected at that tip. Once the light reaches the tip array, themechanical compliance of the tips in the array and the nanoscale size ofthe apertures in the array allow the tip array to perform near-fieldlithography (for example, in the embodiment illustrated in FIG. 1A) orto selectively actuate the tips by activating heaters disposed on thetip array, as described in detail below.

FIGS. 28 and 31 illustrate examples of complex patterns that can beadvantageously formed using projected lithography.

In accordance with embodiments of the disclosure, a tip array havingindividual addressability of tips provided by selectively and locallyheating the tips of a tip array is provided. The heat actuable tiparrays can be used alone or in connection with the pBPL system describedherein. As discussed in detail below, the heat actuable tip arraysinclude tips disposed on a common elastomeric tip substrate layer andcan be selectively actuated by selective heating of portions of theelastomeric tip substrate layer in the region of the tip or tips to beactuated. As illustrated in FIG. 10A, heating of the tip substrate layerthermally expands the heated region of the tip substrate layer, therebylowering (in the orientation illustrated) the tip disposed in the heatedregion relative to tips disposed in an unheated region of the tipsubstrate layer. In one type of embodiment, heaters are disposed on thecommon substrate layer to provide for the selective actuation of thetips. In another, non-exclusive type of embodiment, heaters are disposedon the backs of the tips to provide for the selective actuation of thetips. Advantageously, the heaters can be photo-activated heaters, forexample, and can optionally be activated in connection with theprojected lithography system described herein, althoughnon-photo-activated heaters are also contemplated.

In any of the patterning methods disclosed herein, it should beunderstood that the tip arrays can be intentionally tilted relative tothe substrate, such as is described in International Patent PublicationNo. WO 2011/071753.

Projected Lithography System

Projected pen lithography is a lithography system that may include a tiparray coupled with a projector, for example, a digital micromirrordevice (DMD), to direct light to specific locations on a surface withspatial high resolution. Various embodiments of tip arrays may be usedwith projected lithography including a beam pen lithography tip arrayand a heat actuated tip array as described in detail below.

In a projected lithography system, a tip array may be combined with aprojection system to allow for rapid patterning of sub-100 nm featuresin arbitrary arrangements across a large (e.g., cm-scale) surface. Someembodiments of projected lithography may represent a significant advancein capabilities over conventional tip-based lithography systems. Forexample, in projected lithography systems, a projector may allow thesubstrate to be patterned in any conceivable pattern, versusconventional lithography in which typically copies of the same patternare written in parallel by all tips. Further, in embodiments in whichthe tip array is a beam pen lithography tip array, the size of featuresmay be controlled through the intensity of light used in pBPL. Thus,pBPL may allow for different tips in the array to create different sizedfeatures.

FIG. 1A illustrates a system for projected lithography 100, though anysuitable lithography platform may be used in the systems and methodsdescribed herein (e.g., a Park AFM platform such as a XEP made by ParkSystems Co., Suwon, Korea or platforms made by NanoInk Inc., Skokie,Ill.). The system 100 may include any number of computing devices andcomponents that are communicatively coupled via a network such as theInternet or other type of networks (e.g., LAN, a MAN, a WAN, a mobile, awired or wireless network, a private network, or a virtual privatenetwork, etc.). Each component of the system 100 may include a processorconfigured to execute instructions of one or more instruction modulesstored in computer memory.

The system 100 may combine a tip array 102 on a translational stage witha light projection system 104 to form a platform for writing patterns ona surface 106. The tip array 102 may include millions of elastomericpyramidal tips. It should be understood herein that radiation sourcesother than light can be used with the systems described herein. The useof the term “light” should be understood to include any suitablewavelength of radiation and any suitable radiation source unlessspecified otherwise. Various types of tips arrays may be used, asdescribed in detail below. In one embodiment, the projected lithographysystem includes a beam pen tip array, which includes tips having a nearfield aperture for exposing a substrate with irradiation. The projectedradiation selectively activates the tips of the tip array by passingthrough activated tips to expose the substrate. In another embodiment,the projected lithography system includes a heat actuated tip array. Asdiscussed in detail below, such tip arrays include a tip substrate layerhaving tips extending from a first surface of the tip substrate layerand an array of heaters disposed on a second surface opposite the firstsurface. The heaters can be photoconductive heaters, which are activatedupon exposure to radiation. In such embodiments, the projectedlithography system projects a pattern of radiation onto the heaters ofthe tip array to selectively activate irradiated heaters and therebyheat the tip substrate layer in the region of the heater and lower (asshown in the orientation of FIG. 10A) the tip in the region of theheated tip substrate layer. Methods of patterning using heat actuationof tips are described in detail below. The projected lithography systemdescribed herein can be used as the radiation source and control systemfor the selective activation of the heaters.

Various hardware and software components may direct light to the surfaceof the tip array 102 at predetermined times in coordination withscanning, for example, raster scanning, of the tip array with respect toa surface. The array 102 may include any of the various embodiments fora tip array as herein described.

The projected lithography system 100 can utilize a modified Park SystemsXE-150 Scanning probe platform. The tip array 102 may be magneticallymounted on a scanner head 108. The head 108 may include a square framewith a 1×1 cm² aperture to allow optical addressing of each tip in thearray 102. The scanner head 108 may be vertically (z-direction)positioned by a piezoelectric driver on the head. Samples forlithography may be held on a vacuum chuck on a stage 110 below the headwhich may be positioned in X and Y dimensions with stepper motors forcoarse positioning and piezoelectric scanners for fine positioning.Additionally, the sample may be rotated with stepper motors (roll andpitch) to level the sample with respect to the beam tip array 102. Adigital micromirror device (DMD-DLP LightCommander-Logic PD) 112 canallow the system 100 to project spatial patterns onto the tip array 102.A collimated light source 114 (e.g., a collimated 440 mW 405 nm LEDlight source such as a M405L2 made by Thor Labs USA) may be used inconjunction with a digital light processing projector (DLP) with a macrolens (e.g., AF Micro-Nikkor 200 mm f/4D IF-ED) 116 to focus an imagegenerated by the DMD 112 onto the surface of the beam tip array 102. Theimage projected by the DMD 112 onto the surface of the tip array 102 maybe controlled by a first computer 118 including a processor 118 a andmemory 118 b. In some embodiments, the processor 118 a executesinstructions stored in the memory 118 b. For example, the instructionsmay include custom software written in a technical computing language(e.g., MATLAB, The Mathworks Inc.). Alignment between the projectedimage and the tip array 102 may be monitored by a camera 120 (e.g., adigital camera such as a CCD camera like the PLB782 made by PixeLINK).This alignment may be adjusted using an interface (e.g., a MATLABinterface executing on the first computer 118). During printing, themotion of a scanning probe microscope 122 (e.g., a Park XE-150) may becontrolled by a second computer 124 including a processor 124 a andmemory 124 b that stores scanning probe software instructions forexecution using the processor 124 a. The state of the projector 116 maybe controlled by the first computer 118. To coordinate the actions ofthe first computer 118 and the second computer 124, the first computer118 may monitor the voltage supplied to the z-piezo through a dataacquisition module (DAQ) 126 (e.g., a NI-USB 6212). As described herein,arbitrary patterns may be created by projecting a series of images asthe scanning probe instrument scans across the surface to be patterned.

In another embodiment, the system 100 may include a Zeiss microscopewith a light source having a wavelength in a range of about 360 nm toabout 450 nm. Movement of the tip array 102 when using the Zeissmicroscope may be controlled, for example, by the microscope stage 108.

In various embodiments, the projector 116 includes the DMD 112 and themacro lens 116 a for focusing the irradiation pattern emitted by the DMD112 onto the tip array 102. The digital micromirror device can includeany commercially available device having a suitable radiation source forthe desired patterning. Historically, photolithography has usedultraviolet light from gas-discharge lamps using mercury, sometimes incombination with noble gases such as xenon. These lamps produce lightacross a broad spectrum with several strong peaks in the ultravioletrange. This spectrum is filtered to select a single spectral line, forexample the “g-line” (436 nm) or “i-line” (365 nm). More recently,lithography has moved to “deep ultraviolet,” for example wavelengthsbelow 300 nm, which can be produced by excimer lasers. Krypton fluorideproduces a 248-nm spectral line, and argon fluoride a 193-nm line. Inprinciple, the type of radiation used with the present apparatus andmethods is not limited. One practical consideration is compatibilitywith the tip array 102 materials chosen and the digital micromirrordevice. For example, the radiation can be in the wavelength range ofabout 300 nm to about 600 nm. For example, the radiation optionally canhave a minimum wavelength of about 300, 350, 400, 450, 500, 550, or 600nm. For example, the radiation optionally can have a maximum wavelengthof about 300, 350, 400, 450, 500, 550, or 600 nm. In some embodiments,the wavelength can be greater than 400 nm to avoid damage to a digitalmicromirror device 112. For example, the wavelength can be about 405 nm.An exemplary commercially available digital micromirror device 102 isthe DLP5500 (Texas instruments). In various embodiments, thecommercially provided light source can be replaced with a collimated 440mW 405 nm LED light source (M405L2—Thor Labs USA). The digitalmicromirror device DLP550 chip is a 0.55″ chip with 10.8 μm pitch pixelswith XGA resolutions (1024/758 independent pixels).

Any commercially available lens having a suitable minimum focal length,for example, of about one foot, can be used for the macro lens 116 a.Nikon f-mount lens, such as 105 mm f/2.8 G ED-IF AF-S VR Micro-NikkorLens (Nikon), are exemplary commercially available lenses suitable foruse in pBPL. In various embodiments, a macro lens 116 a having anadjustable focal length is used. The macro lens 116 a can be used toselectively allow the light from multiple mirrors of the digitalmicromirror device 112 to be focused onto a single pen of the tip array,and thus adjust the intensity. Selection of the focal length of themacro lens 116 a in combination with the distance between the tip array102 and the lens 116 a can be used to tailor the number of mirrors thatfocus light on a single pen. For example, the ratio of mirrors focusinglight onto a pen can be in a range of about 1:1 to about 100:1, about10:1 to about 90:1, about 20:1 to about 80:1, about 30:1 to about 70:1,about 40:1 to about 60:1, about 50:1 to about 75:1, 1:1 to about 40:1,about 5:1 to about 35:1, about 10:1 to about 30:1, and about 15:1 toabout 25:1. Other suitable ratios include, for example, about 1:1, 5:1,10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, 60:1, 65:1,70:1, 75:1, 80:1, 85:1, 90:1, 95:1, and 100:1.

Methods of Patterning using Projected Lithography

While the system 100 illustrated in FIG. 1A may include one or moreinstruction modules stored in the memory 118 b for execution by theprocessor 118 a of the first computer 118, some or all of the componentsand functions of the system 100 described herein may also beincorporated on the second computer 124, the controller 104, the DAQ126, etc. Further, any instruction module of the system 100 may beimplemented as a separate module or system.

The irradiation pattern projected by the projector 116 can be controlledusing the first computer 118 including computer software executed by theprocessor 118 a and stored in the memory 118 b to interface with thecontrol system of the lithography system 100. In some embodiments, thesystem 100 may execute instructions for alignment and then execute alithography printing process.

Hardware Alignment of the Projector and Tip Array

The projector and the tip array can be aligned by positioning theprojector, for example, a digital mirror device, a suitable distancefrom the tip array. In various embodiments, the distance issubstantially equal to the focal length of a macro lens of theprojector.

The macro lens, the digital mirror device, and optionally a beamsplitter can be aligned in a generally parallel plane. For example,alignment can be achieved using an optical breadboard in which the holesof the optical breadboard are utilized to achieve parallel alignment. Atest pattern, for example, a pattern of dots, can be projected from theprojector (for example, the digital mirror device) onto a back plane ofthe tip array. When a beam splitter is used, a camera can be focused toobserve the back plane of the tip array through the beam splitter. Theposition of the digital mirror device can then be adjusted to center thetest pattern on the tip array.

In embodiments utilizing a beam splitter, the position of the beamsplitter can be adjusted until a roughly focused irradiation pattern isobserved, for example, by a camera focused on the beam splitter.

The focal length of the macro lens can then be adjusted until the edgeof the test pattern is sharp and clearly observed by a camera, if used.In various embodiments, the focal length of the macro lens can beadjusted to selectively adjust the number of mirrors focusingirradiation on a single pen of the tip array. For example, about 1 toabout 50 mirrors can focus irradiation on a single pen. Other examplesof the number of mirrors that can focus irradiation on a single peninclude a range of about 2 to about 45, about 4 to about 40, about 6 toabout 35, about 8 to about 30, about 10 to about 25, about 12 to about20, and about 14 to about 18. For example, about 1, 2, 3, 4, 5, 6, 7, 8,9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26,27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44,45, 46, 47, 48, 49, or 50 tips can focus irradiation onto a single pen.

The test pattern can then be checked for distortion across the entiretip array to ensure that the focal plane of the macro lens is parallelto the plane of the tip array.

FIG. 2A illustrates an alignment user interface 200 and FIG. 2Billustrates a block diagram of a method 250 for aligning the system 100for executing a lithography printing process. As described below, theuser interface 200 may facilitate execution of other instructions storedin the memory 118 b to complete the alignment.

The method 250 may include one or more blocks, modules, functions, orroutines in the form of computer-executable instructions that are storedin a tangible computer-readable medium and executed using a processor(e.g., processor 118 a) of a computing device (e.g., the first computingdevice 118). The methods may be included as part of any modules of acomputing environment for the lithography system 100, or as part of amodule that is external to such a system. For example, the methods maybe part of the second computer 124, the controller 104, an AFM 122, aDAQ 126, or other system component. FIGS. 2a and 2b will be describedwith reference to other figures for ease of explanation, but the methodsmay of course be utilized with other objects and user interfaces.

Alignment between the light projected from the projector 116 and thebeam tip array 102 is necessary to achieve individual addressability ofeach tip in the array. Since the DMD 112 is not transparent and designedto redirect light at a specific angle of incidence, it cannot bedirectly attached to the tip array 102. In some embodiments, the DMD 112may be positioned in a far field projection mode where focusing opticsreproduce an image directed by the projector 116 on the surface of theDMD 112 on a distant object. With a combination of optical and softwareadjustments, the alignment process may ensure that the pattern generatedby the DMD is reproduced in focus and in the correct location of thebeam tip array 102.

With reference to FIG. 2B, at block 252, a light pattern generated bythe DMD may be focused on the plane of tip array 102 with minimumdistortion. In one embodiment, a lens with a minimum focal length oftwelve inches (30.5 cm) may be employed to focus the light from the DMD.At block 254, the light pattern may be guided onto the scanning probeplatform and reflected onto the beam tip array by a beam splitter.Generally, the distance between lens 116 a and tip array 102 should beidentical to the focal length of the lens 116 a and the focal plane ofthe light pattern needs to be parallel to the plane of tip array 102,otherwise only part of the tip array 102 will be in focus. To accomplishthis manual adjustment, at block 256, the light pattern on the tip array102 may be monitored by the camera 120.

FIG. 2C illustrates one method 275 for monitoring the light patternusing the camera 120. At block 276, the DMD 112 may be positioned afixed distance from a head of the scanning probe microscope 122. In someembodiments, the method 275 may position the DMD ten inches (25.4 cm)from the scanning probe head. At block 278, the method 275 may align thecenter lens 116 a, a beam splitter, and a mirror 128. In someembodiments, block 278 may include instructions to use a rectangulararray of holes in the optical breadboard of the microscope 122 as astarting point. At block 278, the method may display a test pattern withthe projector 116 and use the visible light to fine tune this alignment.At block 280, the method may fine tune the alignment by engaging thecamera 120 to observe the back plane of tip array 102 through a beamsplitter. At block 282, the method 275 may focus the camera until aclear image of the tips of the tip array is observed. At block 284, themethod may adjust the position of DMD 112 in both horizontal andvertical direction to make sure the light pattern is centered on the tiparray 102. In some embodiments, the position of the DMD may be adjustedwith finely adjustable mechanical standings. At block 286, the methodmay adjust the position of the beam splitter until a roughly focusedlight pattern is observed by the camera and at block 288, the method mayadjust the focal length of the projector lens until the edge of lightpattern is sharp and clearly observed by the camera. At block 289, themethod may check the distortion of light pattern across the whole beamarray to make sure the focal plane of lens is parallel to the plane oftip array. If the pattern is out of focus, the method may repeat blocks282-288 until the pattern is as crisp as possible.

Software Alignment of the Projected Image and the Tip Array

Referring to FIG. 2E, the projected image and coordination of thesoftware program controlling the projection of the irradiation patternscan be aligned using a checkerboard irradiation test pattern. A firsttest pattern can be projected onto the tip array. For example, the firsttest pattern can be a checkerboard pattern. The first test pattern has alarge ratio of L/N, such that each illuminated region of the testpattern contains at least a 5×5 array of tips (FIG. 2E, left and centerimages). N refers to the number of tips on an edge of the test patternand L is the number of mirrors on an edge of the test pattern. The ratioL/N describes how many mirrors address each tip. N2 is the total numberof tips in the test pattern. For example, in a checkerboard testpattern, N2 is the total number of tips in a single illuminated square.L2 is the total number of mirrors in the illuminated portion of the testpattern, for example an illuminated square of a checkerboard testpattern. The arrangement of the tips of the tip array in the testpattern is observed, for example, using a camera focused on a beamsplitter, to determine whether any of the tips in the illuminated squareregion cross an edge of the square region. If one or more tips cross theilluminated square region, the test pattern is rotated until the tipsare aligned along the edge of the illuminated square region. Rotation ofthe test pattern accounts for any rotation of the tip array. Oncerotational alignment of the first test pattern and the tips of the tiparray is achieved, a second test pattern, for example, a checkerboardtest pattern, is projected onto the tip array. The second checkerboardtest pattern has an increased N value such that a single pen is in asingle illuminated square of the second test pattern (FIG. 2E, rightimage). For example, where the first test pattern is selected such thateach illuminated square of the test pattern contains a 5×5 array oftips, the second test pattern is selected to have a value of 5N, whilemaintaining the same L value of the first test pattern. The secondcheckerboard pattern is then observed on the tip array, for exampleusing a camera through a beam splitter, and the second test pattern isadjusted in the x and y directions to center each pen in the illuminatedsquare, thereby aligning the projected pattern with the tip array. Therotational and translational adjustments made to align the test patternsare maintained within the software program, which utilizes such valueswhen projecting irradiation patterns for patterning a substrate toensure alignment of the projected irradiation pattern and the tip array.

FIG. 2D illustrates a block diagram of a method 290 to further align thesystem 100 for executing a lithography printing process. While method275 aligns the optical hardware 104 to the tip array 102, there maystill be no registry between the tips in the array and the pixels in theDMD 112. Thus, the method 290 generally adjusts the parameters of theDMD 112. With reference to FIG. 2A, a checker board pattern image 202may be displayed on the projector 116. The size, orientation, andposition of the image 202 may be adjusted in software until theprojected image matches the tips in the array 102. For example, “X” 204and “Y” 206 may determine the center of the checker board; “Rotation”208 may allow for compensation if the beam tip array is slightlyrotated, “L” 210 may include the edge length of the board counted asmirrors in the DMD while “N” 212 may include the edge length of theboard in tips on the tip array. “L/N” may give the period of the checkerboard, and also dictates how many mirrors direct light to each pen.Mirrors in the DMD are grouped in this way by the method 290 to achieveone to one correspondence with the BPL tips. To tune this alignment, themethod 290 may monitor the image 202 projected on the surface of thebeam tip array 102.

At block 291, the rotational mismatch is the first parameter to betuned. A large value of L/N may be selected so that more than 5×5 tipsare located in one square. By checking across the tip array 102, themethod 290 may determine if any row or column of tips crosses the edgeof square. If they do, the rotational angle needs to be adjusted. Avalue of the Rotation 208 may be changed to ensure the light pattern isfinally in the same rotational angle of the tip array. At block 292, themethod may adjust the L value 210 and the N value 212 to approach acoarse value of L and N.

In some embodiments, the values are adjusted to have 5×5 tips in eachsquare. At block 293, the method may adjust the X value 204 and the Yvalue 206 to center the tips in the squares. At block 294, the N value212 may be changed to the number reflecting the number of tips in eachsquare. In some embodiments, the method adjusts the N value to five. Atblock 295, the method may further adjust X and Y values slightly to makesure each pen is in the center of each square. At block 296, the methodmay check all the tips across the whole array to see if any mismatchesstill exist. If mismatches still exist, then the method 290 may returnto block 291. If not, then the alignment process may end. At thecompletion of the method 290, the optical path is aligned and thecorrespondence between mirrors in the DMD and tips in the tip array issaved in the system (e.g., memory 118 b, 124 b). With reference to FIG.3, instructions stored in the memory 118 b may cause the processor 118 ato display a user interface 300 on the first computer 118. As describedbelow, the user interface 300 may facilitate execution of other moduleinstructions to complete the lithography process using the system 100.

FIG. 4 is a flow diagram of example a method 400 for completing alithography process using the system 100. The method may include one ormore blocks, modules, functions, or routines in the form ofcomputer-executable instructions that are stored in a tangiblecomputer-readable medium (e.g., memory 118 b) and executed using aprocessor (e.g., processor 118 a) of a computing device (e.g., the firstcomputing device 118). The method may be included as part of any modulesof a computing environment for the lithography system 100, or as part ofa module that is external to such a system. FIG. 4 will be describedwith reference to other figures for ease of explanation, but the method400 may of course be utilized with other objects and user interfaces.

At block 402, a module stored in the memory 118 b may cause theprocessor 118 a to subdivide a selected image 302 to be patterned onsubstrate into geometric sections (also referred to herein as “frames”).The geometric sections can have substantially the same size and shape asthe tip array 102. For example, where the tip array has tips generallyarranged in a rectangle or square, the frame section can becorrespondingly shaped in a rectangle or a square. Other frame sectionshapes, including, hexagonal and triangular, can be used where the tipsare arranged in such shapes on the tip array. The image 302 can bedivided into any suitable number of geometric sections such that eachpixel of the image is addressed by a tip of the array 102 in a geometricsection. The geometric sections can optionally overlap such that pixelshaving spacing of less than the tip pitch, and thus not addressable by atip in a first geometric section, can be addressed by a tip in a second,overlapping geometric section.

Once the image is divided into the geometric sections, block 404 maycause the processor 118 a to execute an instruction stored in the memory118 b to determine a tip pattern for each geometric section. The tippattern corresponds to the portion of the image 302 to be patterned bythe tips of the tip array in a given geometric section. Determination ofthe tip pattern can include determining which tips will be selectivelyilluminated to pattern the portion of the image 302 in the geometricshape and optionally the intensity of the radiation that will besupplied to each tip that is selectively illuminated. For example,within a given tip pattern radiation directed to one or more tips can beselectively modulated during patterning to allow for patterning in withvariable intensity (e.g. “grayscale” 304), whereby tips of the tip arrayare capable of patterning different sized features in a single printingoperation.

At block 406, the method 400 may generate an instruction file for thetip array system 100. The instruction file may include furtherinstructions to control movement of the tip array across the substrateto each geometric section. The instruction file can further dictate tothe tip array system the allotted time for each patterning operation ingiven geometric section, as well as the travel time of the tip arraybetween geometric sections. For example, the user interface 300 mayreceive a desired patterning or exposure time 306, a safety time 308 toensure patterning is complete and the tip array is no longer illuminatedbefore the tip array is moved to the next geometric section. The safetytime 308 may avoid patterning contamination during movement of the tiparray. In embodiments, the safety time 308 can be zero, if no delay isneeded. Additionally, the interface 300 may receive a delay time 310,which may ensure that the tip array is in position for patterning priorto illumination of the tip array. For example, the instruction file mayinclude instructions to cause the system 100 to maintain a tip array ina given geometric section for a time equal to the sum of the delay time310, the patterning or exposure time 306, and the safety time 308. Bygenerating the instruction file for instruction movement of the tiparray 102, the location of the tip array is known and predictable suchthat a given pattern of radiation can be generated by the projector 116to selectively illuminate the tip array in a given tip pattern for agiven geometric section.

In one exemplary patterning operation, at block 408, the system 100 canmanipulate the tip array 100 to a first geometric section and lower thetip array into a patterning position. For example, block 408 may causethe tip array to be lowered adjacent to the substrate, but notcontacting the substrate or can be contacting the substrate at aselected degree of pressure, depending on the desired feature size. Atblock 410, the method may detect a z-piezo voltage of the tip array 102.The z-piezo voltage may indicate a vertical position of the tip array102 relative to the substrate 106. Once a threshold voltage is detected,block 412 may cause the system 100 to wait a set delay time 310 before,at block 414, causing the projector 116 to project the a first patternof radiation to selectively illuminate the tip array 102 and expose thesubstrate 106 in a first tip pattern corresponding to the portion of theimage to be patterned in the first geometric section. The thresholdvoltage is indicative of the tip array being in the patterning position.Selective illumination of the tip array 102 results in exposure of thesubstrate in the first tip pattern. After lapse of a set exposure orpatterning time, at block 416, the method 400 may cause the projector116 to cease projection of any radiation into the tip array. At block418, the method 400 may cause the tip array to be maintained in thefirst geometric section for a set safety time 308 before, at block 420,determining if other sections require patterning. If so, then the method400 may return to block 408 and cause the array 102 to be lifted awayfrom the substrate and moved to a second geometric section. Once at thesecond geometric section, the tip array is again lowered into apatterning position, generating a threshold voltage for detection by theprogram. Once the threshold voltage is again detected, the programinstructs the projector to project a second pattern of radiation toselectively illumination the tip array and expose the substrate in asecond tip pattern corresponding to the portion of the image to bepatterned in the second geometric section. This process can be repeateduntil each geometric section has been addressed by the tip array and themethod 400 ends. As the person of ordinary skill in the art willappreciate, if patterning is performed without the array touching thesubstrate, then the raising and lowering of the array may beunnecessary, and the method can omit such steps.

In some embodiments, the system 100 may include thermally-actuated tiparray. With reference to FIG. 5, a system 500 may include a power amp502 to provide a voltage to heaters at the tip array 504. For example,projecting the a pattern of radiation (as described above in FIGS. 1-4and the accompanying text) may selectively expose the heaters to suchradiation to selectively activate the exposed heaters to locally heat aheating zone of the tip substrate layer and lower (as pictured) one ormore tips disposed in the heating zone into contact or closer contactwith the substrate, as further described below.

The pattern of radiation projected by the projector can includeselective illumination of the tips of the tip array, as well asselection of the dose of radiation illuminating each tip. For example,the projector 116 can include a digital micromirror device 112, in whichone or more mirrors selectively illuminate a tip and such mirrors can beactuated at a given rate or duty cycle to control the dose of theradiation illuminating a given tip. Such control can allow for thepatterning in “grayscale” in which different tips are capable ofpatterning different feature sizes in a single patterning operation andwith the tip array being oriented level with respect to the substrate.In various embodiments, the instruction file can further includeinstructions for tilting the tip array for generation of varyingfeatures sizes in given geometric section by patterning with the tiltedarray.

Thermal Actuation of Tips of the Tip Arrays

In various embodiments of the disclosure, a tip array having a pluralityof tips disposed on a common elastomeric tip substrate layer can beselectively actuated by selective heating portions of the elastomerictip substrate layer in the region of the tip or tips to be actuated. Asillustrated in FIG. 10A, heating of the tip substrate layer thermallyexpands the heated region of the tip substrate layer, thereby lowering(in the orientation pictured) the tip disposed in the heated regionrelative to tips disposed in an unheated region of the tip substratelayer. Individual actuation can advantageously allow the tip arrays toprint continuous patterns over cm-scales, print independent patternswith different patterning compositions, and/or use different dwell timesand extensions for different tips to print different size features withdifferent tips of the tip array. Individual actuation can also allow forsimple and rapid selective inking of tips of a tip array with one ormore patterning compositions.

In accordance with an embodiment of the disclosure, the tip arraysgenerally include an array of heaters disposed on a second surface ofthe tip substrate layer opposite the first surface having the tips. Theone or more heaters of the array can be selectively activated to locallyheat a region of the tip substrate layer and lower the tip or tipslocated in the heated region as compared to the tips located in a regionof the tip substrate layer that remains unheated. For example, themethod of selectively actuating a tip array using heat can includeleveling the tip array relative to the substrate. Optical and forcefeedback leveling methods can be used as is known in the art. In anembodiment, the tips of the tip array can be held a distance above thesubstrate, for example, a few micrometers away from the substrate. Theactivation of the heater can then be used to selectively bring each tipor a region of tips into contact with the substrate. In anotherembodiment, the tips of the tip array can be placed into contact withthe substrate. Activation of one or more heaters can be used toselectively bring each tip or a region of tips into closer contact withthe substrate, thereby forming pattern features of different sizes byrelying on the force dependent nature of feature size when patterningwith the various tips.

The tip array generally includes a tip substrate layer comprising afirst surface and an oppositely disposed second surface. A variety oftip array systems including polymer pen tip arrays, beam pen tip arrays,hard tip soft spring arrays (also referred to herein as silicon pen tiparrays), a graphene coated tip arrays are described in detail below.Each of these tip arrays can be modified to include a heater disposed onthe tip substrate layer to achieve thermal actuation of the tips inaccordance with embodiments of the disclosure. In each of the varioustypes of tip arrays, for purposes of thermal actuation the tip substratelayer is formed of an elastomeric material capable of thermallyexpanding when heated. The tip substrate layer can be selected to have ahigh coefficient of thermal expansion, for example, about 10⁻⁴ perdegree Kelvin, which allows a tip to be actuated a significant distanceupon localized heating of the tip substrate layer. PDMS has acoefficient of thermal expansion of about 3×10⁻⁴ per degree Kelvin.Additionally, the small volume of material in the locally heated regionof the substrate layer allows the material to be rapidly heated andcooled. The tip substrate layer can also be an elastomeric materialhaving a low thermal conductivity, such as PDMS. Using low thermalconductivity materials can allow the heat generated by the heater to belocalized in the tip substrate layer. Additionally, by virtue of theelastomeric nature of the materials, once the heat dissipates from thematerial, the thermally expanded material will recover, returning to itsoriginal non-expanded form, thereby raising the selectively actuatedtip.

The tip array further includes a plurality of tips fixed to the firstsurface of the tip substrate layer and having a tip end disposedopposite the first surface of the tip substrate layer. A detaileddescription of the tips of various suitable tip arrays is providedbelow.

One or more heaters are disposed on the second surface of the tipsubstrate layer. For example, the heaters can be disposed on a supportlayer, and between the support layer and the tip substrate layer. In oneembodiment, the tip array includes a plurality of heaters such that asingle heater is disposed above each tip of the tip array. For example,FIG. 10C illustrates an embodiment in which a single heater correspondsto each single tip of the tip array. In another embodiment, the tiparray can include one or more heaters disposed in a zone of the tipsubstrate layer corresponding to a heating zone that includes a subsetof the tips of the tips array. Any suitable number of tips can beincluded in the subset of tips. In such an arrangement, activation of aheater can result in the actuation of the subset of tips of the tiparray.

In an embodiment, the heater in a zone can be adapted to heat the zonein a gradient fashion such that regions of the tip substrate layer inthe zone disposed nearest the heater exhibit increased thermal expansionas compared to regions of the tip substrate in the zone disposed awayfrom the heater. This, in turn, can result in a gradient of lowering ofthe tips disposed in the zone. A tip array can be divided into anysuitable number of zones having any number of tips in each zone. Thezones can each include the same or a different number of tips dependingon the application.

Actuation of the heaters can be controlled, for example, by wiring eachheater directly to an electronic switch. For example, a distinct wirecan be connected to the heater of each tip or each heating zone and anelectrical control can be used to activate the heaters selectively. Theheaters can be formed of indium tin oxide (ITO), graphene,poly(3,4-ethylenedioxythiophene) (PEDOT), gold, copper, platinum, andcombinations thereof.

As described in detail below, a control system can be used to controlactuation of the tips. In another embodiment, active memory elements canbe fabricated on the same substrate as the tip array. Using such amemory system, the state of the entire array can be loaded using fewerwires by dividing the signal in time. In some embodiments, the tip arrayneed not remain translucent allowing for increased flexibility in heatermaterial and the application of such memory systems. In suchembodiments, the tip array can be leveled by force feedback leveling asknown in the art.

Alternatively, the heaters can be made out of a photoconductive materialthat can be activated by irradiating the heater with an irradiationsource, for example, visible and/or UV light. Photoconductive materialsexperience a dramatic change in electrical conductivity in response toirradiation. For example, the irradiation can cause the electricalconductivity of the heater to increase, thereby allowing the heater toheat. A voltage can be applied across the photoconductive heaters, whichact as a radiation-controlled electrical switch that only allows thecurrent will only flow if irradiation is applied. In this way, theirradiation can be used to select which heater is activated while thepower for heating is supplied electrically using only two wires for amuch simpler array design. Any suitable photoconductive material can beused. If optical leveling is utilized, the photoconductive material ispreferably translucent, and more preferably transparent. Suitablematerials include, for example, amorphous hydrogenated silicon, zincoxide, graphene, CdS, CdSe, ZnS, ZnSe, PbS, SnS, Bi₂S₃, Bi₂Se₃, Sb₂S₃,CuS, CuSe. Each of these materials can achieve a ratio of illuminated todark conductivity, for example, of over 10².

In one embodiment, the heat actuation tip array can include multiplephotoconductive heaters, the heaters being activated at differentwavelengths. The heaters can be selectively activated by controllingvarious irradiation sources having wavelengths for selectivelyactivating only certain heaters. This can advantageously be used toallow for general irradiation of a tip array with an irradiation havinga wavelength for only a subset of the heaters, thereby allowing forselective actuation without selective irradiation. In other embodiments,the tip array can be selectively actuated by selectively irradiatingphotoconductive heaters. For example, the tip arrays can further includean array of spatial light modulators disposed on the tip substrate layerto selectively expose a heater to allow for selective irradiation of theheaters. The spatial light modulators can be, for example, dynamicallycontrollable. In another embodiment, as described in detail below, theheat actuation tip arrays can be used in connection with the projectedlithography system and irradiation images can be projected onto theheaters of the tip array to active the heaters and selectively actuatethe tips. In one embodiment, tip array is a beam pen tip array thatincludes an array of heaters for selectively actuating the beam pentips. In such embodiments, the wavelength for activating the heaters andfor patterning (i.e., exposure of the substrate) can be the same or canbe different wavelengths. For example, in one embodiment, the beam pentip array can be placed in a patterning position not in contact with thesubstrate. A radiation source for patterning can be focused on the tiparray and an radiation source for activating the heaters can be used inconnection with the projected lithography and projected onto the heatersin patterns of radiation for selectively actuation the tips to be incontact or near-field contact with the tip array, thereby activating thetip to expose the substrate. In the patterning position, the tips aredisposed at a distance at which exposure does not occur, despite thetips being illuminated. Thus, it is upon selective actuation of the tipsby the activation of a heater that the tips are activated forpatterning.

FIG. 15 illustrates a comparison of the heaters using the direct wire(FIG. 15A) and the photoconductive (FIG. 15B) embodiments. While theelectrical actuation scheme incorporates a coil heater that is switchedon an off by a transistor, in the photo-active scheme, incidentirradiation increases the electrical conductivity of a photoconductivedisc which functions both as the heater and as the switch.

Any suitable heaters can be used. For example, the heaters can beresistive heaters or photoconductive heaters. In various embodiments theheaters are substantially transparent. By providing substantiallytransparent heaters, the tip arrays can be optically leveled as is knownthe art. Optical leveling is described, for example, in U.S. PatentApplication Publication No. 2011/0132220, the entire disclosure of whichis incorporated herein by reference. In alternative embodiments, theheaters are opaque. In such embodiments, the tip arrays can be leveledusing force feedback leveling, as is known in the art. Force feedbackleveling is described, for example, in U.S. Patent ApplicationPublication No. 2011/0165329.

An example of a printed pattern is shown in FIG. 14. Here, the patternwas formed by inking the tips in a solution of 16-mercaptohexadecanoicacid (MHA) in ethanol. The tips were then used to generate a patterncorresponding to a region of the periodic table of the elements. MHAtransfers to the gold surface, forming a self-assembled monolayer whichprotects patterned regions from a chemical etch that is selective forgold. Final patterns were visualized by scanning electron microscopy. Inthe 4×4 actuation scheme presented here, each probe was actuated inseries, meaning there is never a time when two tips are simultaneouslylowered into contact with the substrate. Selectively lowering only onetip at a time can be used mitigate crosstalk between tips. Inalternative embodiments, multiple tips can be selectively lowered at thesame time.

Mitigating crosstalk or interference with selection of the tips can beachieved by examining the heat profile of the heaters and dividing thetip array in to sub-grids accordingly. Interference can be mitigated byonly simultaneously activating sub-grid regions that do not haveoverlapping heat profiles. For example, based on the characterization ofthermal actuation presented in FIG. 12D, this can be achievedconservatively by dividing up the array into 9 sub-grids that are alladdressed in sequence. This presents a good compromise betweenthroughput and protection against crosstalk.

In accordance with embodiments of the disclosure, a tip array having anarray of heaters can be manufactured by defining the heaters on asubstrate, coating the substrate with an elastomeric material layer,defining tip masks that are aligned to the heaters on the substrate, andetching the tip masks to form the tips. In an embodiment in which thetip array is a silicon tip array, the method can include definingheaters on a substrate, coating the substrate with an elastomericmaterial and a thin silicon wafer, defining tip masks in the siliconwafer that are aligned with the heaters on the substrate, and etchingthe tip masks to form the silicon tip arrays having heaters disposed onthe tip substrate layer.

Heaters can be fabricated, for example of indium tin oxide (ITO) byetching an ITO coated glass slide. ITO is transparent and conductive.25×25 mm² glass slides coated with 8 to 12 Ω/sq are commerciallyavailable from Sigma Aldrich. The coated slides can be cleaned, forexample, by rinsing in acetone, DI water, and isopropanol. The samplescan be dried, for example, under nitrogen, and then coated with aphotoresist material. For example, a positive tone photoresist materialsuch as SHIPLEY1805 can be used and can be spin coated at 4000 rpm for40 seconds and then baked for 1 min at 115° C. Any suitable positive ornegative tone photoresist can be used and any suitable coating methodcan be used as is known in the art. Samples can be aligned in a maskaligner and then exposed for a sufficient time, for example 2 seconds,and optionally post-exposure baked for about 1 minute at 115° C.Patterns can then be developed in a suitable developer, for exampleMF-24A (Shipley) for a suitable time, for example, about 60 seconds andthen rinsed and dried. Rinsing can be done using DI water and drying canbe done using nitrogen.

The heater material can be etched using any suitable etching method. Forexample, ITO can be etched using reactive ion etching. For example,samples can be mounted on a 4″ wafer and loaded into a deep reactive ionetch apparatus such as a DRIE-STS Lpx Pegasus. The samples can be etchedunder 200 sccm of Argon that is held at 5 mTorr using 2500 W RF powerand 40 W delivered to the platen. Under these conditions, the etch rateof ITO is approximately 1 Å/s. The completion of the etch can beverified using a multimeter to measure the background resistance and theresistance of the devices. To remove the residual resist, the samplescan be soaked in a suitable remover or cleaning solution, such asRemover PG (Microchem). Heating can optionally be used to facilitateresist removal. For example, removal can be done by soaking in asuitable remover or cleaning solution at an elevated temperature, forexample, 80° C. FIG. 10C is a scanning electron microscopy image of aheater fabricated by the foregoing process, which illustrates a 4×4array of coil heaters and associated bus lines.

Once heaters are formed, the fabrication of the tip arrays can begenerally in accordance with known methods of forming the various tiparrays, but using the substrate having the heaters thereon as thesupport layer onto which the tip array is formed.

FIG. 13A illustrates an embodiment in which heat actuation of a tiparray is used to generate a continuous pattern across the entiresubstrate. In accordance with an embodiment, heat actuation of tiparrays can be used to pattern multiple patterns such that eachpatterning region of the substrate is addressable by the tips. Forexample, the tips can be inked with different patterning compositions(also referred to herein as “inks”) such that each region of thesubstrate can be addressed by each ink. Referring to FIG. 13B, forexample, a tip array can be scanned such that each region of thesubstrate can be accessed by not only the closest tip, but also by theneighboring tips of the tip array. The image of FIG. 13B was generatedusing a tip array having tips with a 150 μm pitch and a piezoelectricscan range of 400 μm was used. Different inks can be applied todifferent tips, then repeating patterns of up to nine (in this example)different inks can be applied such that each region can still beaddressed by a tip with each ink. In FIG. 13B, four tips of differentcolors were used to write overlapping patterns. This technique can be ofparticular use when patterning biomolecules with orthogonal chemistriesfor combinatorial screening or diagnostics is important.

In order to ink the tips independently, a Perkin Elmer Piezoarraymicroarraying system can be used. This equipment can print droplets assmall as 333 pL, which corresponds to a width of about 7 μm, and patternthem with micrometer-scale accuracy and registration. Using thisinstrument, multiple varieties of ink can be directly deposited on thetip in a regular repeating fashion to create a multiplexed multi-inkpatterning system.

In an alternative embodiment, the tip array can be independently inkedby selectively actuating the tips using the heat actuation system intocontact with one or more ink sources to thereby dip-coat the tips withthe selected inks.

In yet another embodiment, an inking well can be formed using the masterused to form the tip array. An ink or multiple inks can be inserted intothe wells of the tips to ink the tips with a single ink or selectivelyink the tips with multiple different inks. Any other suitable inkingmethods can also be used.

FIG. 6 illustrates one example of a thermally-activated lithographysystem 600. With reference to FIG. 6, one embodiment of athermally-activated lithography system 600 may include a controlcomputer 604 including a processor 604 a and memory 604 bcommunicatively coupled to an atomic force microscopy (AFM) controller606. The controller 606 may be communicatively coupled to an atomicforce microscope (AFM) 608 such as, for example, the XE-150 AFM producedby Park Systems of Santa Clara, Calif. The AFM may include a tip array602 (e.g., a hard-tip array) including a plurality of tips forimplementing the various lithography processes described herein, inplace of a traditional AFM probe. The system 600 may include othercomponents to receive data from the AFM 508 or send data to the AFM 608to execute lithography operations. For example, the system 600 mayinclude an actuation computer 610 with a processor 610 a and memory 610b in communication with a data acquisition component (DAQ) 612 toreceive feedback data from the AFM 608 or send printing commands to theAFM 608.

The system 600 may include any number of computing devices andcomponents that are communicatively coupled via a network such as theInternet or other type of networks (e.g., LAN, a MAN, a WAN, a mobile, awired or wireless network, a private network, or a virtual privatenetwork, etc.). Each component of the system 600 may include a processor(e.g., 604 a, 610 a) configured to execute instructions of one or moreinstruction modules stored in computer memory (604 b, 610 b). Forexample, the actuation computer 610 memory 610 b may store one or moremodules including instructions for execution by the processor 610 aduring operation of the system 600, as herein described. In someembodiments, the modules may include instructions that, upon execution,cause the processor 610 a to generate an instruction set to complete alithography process as herein described. For simplicity, the actuationcomputer 610 is illustrated with a single processor 610 a to executevarious modules stored in the memory 610 b, as described herein. Theactuation computer 610 in other embodiments may include additionalprocessing units (not shown).

The instruction module stored within the memory 610 b may includeinstructions that, when executed by a processor (e.g., processor 610 a)generate the instruction set for the AFM 608 as well as instructions fora tip array 602 to complete a lithography action. In one embodiment, thememory 610 c includes instructions to break an image of a desiredpattern into regions corresponding to a tip array 602 of the AFM 608;receive a plurality of patterning parameters; generate a patterningfile; load the patterning file; and cause the system 600 to generate alithography image. Of course, the memory 610 b may include any number ofadditional instructions to generate an instruction set and complete alithography process, as described herein.

Method for Electrical Control of Heat Actuated Tip Arrays

With reference to FIG. 7, the memory 710 b may also include instructionsto display a user interface 700 on the module actuation computer 710. Asdescribed below, the user interface 700 may facilitate execution ofother instructions to complete the lithography process.

FIGS. 8A to 8D are flow diagrams of example methods for completing alithography process. The methods may include one or more blocks,modules, functions, or routines in the form of computer-executableinstructions that are stored in a tangible computer-readable medium andexecuted using a processor (e.g., processor 604 a, 610 a) of a computingdevice. The methods may be included as part of any modules of acomputing environment for the lithography system 600, or as part of amodule that is external to such a system. For example, the methods maybe part of the actuation computer 610, the control computer 604, thecontroller 606, an AFM 608, a data acquisition component 612, or othersystem component. FIGS. 8a-d will be described with reference to otherfigures for ease of explanation, but the methods may of course beutilized with other objects and user interfaces.

With reference to the figures, a method 800 (FIG. 8A) may generate aninstruction set for the various lithography processes as describedherein. At block 802, the method 800 may execute instruction to load animage 702 (FIG. 7) corresponding to the desired lithography pattern intothe memory 610 b. In some embodiments, block 802 may includeinstructions to both load the image 702 into the memory 610 b anddisplay the image 702 in the user interface 700. For example, the method800 may execute instructions of block 802 in response to receiving anindication that a user has selected an image file name 704 and a button706 for uploading and storing the image 702.

At block 804, the method 800 may execute an instruction to deconstructthe image 702 for patterning on a substrate by the lithography system600. In some embodiments, instructions of block 804 may break the image702 into regions corresponding to one or more tips of the tip array 602.The geometric regions may have substantially the same size and shape asthe tip array. The image may be divided into any suitable number ofgeometric regions such that each pixel of the image is addressed by atip of the array in a geometric section. The geometric sections canoptionally overlap such that pixels having spacing of less than the tippitch and thus not addressable by a tip in a first geometric section maybe addressed by a tip in a second, overlapping geometric section. Forexample, an image can be pixelated into a black and white500,000×500,000 square grid. The pixelated image can then bedeconstructed into non-overlapping frames 1000×1000 pixels in size, forimaging by a 1,000,000-tip array having 1000×1000 tips in a squarepattern. Thus, the image would be deconstructed into 250,000 frames in a500×500 square grid. Parameters defining the regions may be stored inthe memory as a list or regions that may be used in the lithographypatterning process. For example, block 804 may include instructions todivide the image 702 into a grid of sixteen areas each corresponding toa tip within the tip array 602, where the array 602 includes a four byfour array of tips. Parameters describing these sixteen areas may thenbe stored as a list within the memory 610 a.

At block 806, the method 800 may execute instructions to receivepatterning parameters 708. Generally, the patterning parameters 708prepare the image 702 and system 600 for a lithography process. Theparameters 708 may include a width of the lithography pattern determinedby block 804, as written by each tip, a location of this pattern in thelateral and vertical dimensions, and an angular offset. The angularoffset may be applied to the image 702 to rotate the pattern of thelithography process. In some embodiments, the angular offset parametercorrects for any angular offset between the tip array 602 and the XYpiezoelectric stage. Other received patterning parameters may include adwell time for each tip at a point of the image 702, a travel time ortransit time between subsequent points in the image 702, a delay time,and a safety time. For example, a delay time may indicate a time periodbetween when the DAQ 612 detects that the z-piezo of the AMF is extendedand commencing writing. The safety time may describe an extra timeperiod to ensure patterning is complete before the tip array 602 ismoved to the next geometric section, thereby avoiding patterningcontamination during movement of the tip array. Additionally, asillustrated by the parameters 708, an extension height, lift height, andspeed of the z-piezo may be received as well as a trigger voltage. Themethod 800 may use the trigger voltage to determine when the z-piezo isin an extended or lifted configuration.

At block 808, the method 800 may execute instructions to generate apatterning file. The patterning file may ensure that the location of thetip array is known and predictable such that a given pattern may begenerated so that particular tips of the array 106 a may be activated toaddress a writing action. In some embodiments, the method 800 mayexecute the instructions of block 808 in response to receiving a commandfrom the user interface 700 (e.g., a user selection of the “Update” or“Generate Pattern” button). By generating the patterning file forinstruction movement of the tip array, the location of the tip array isknown and predictable such that a given pattern can be generated in agiven tip pattern for a given geometric section of the image.

With reference to FIG. 8B, a method 820 for generating a patterning filemay include a plurality of instructions that are stored in a memory 610b and executed by a processor 610 a. At block 822, the method 820 mayexecute instructions to analyze the uploaded image 702 to calculate anumber of pixels in width and height that the tip array 602 needs toaddress. At block 824, the method 820 may execute instructions todetermine how many tips within the tip array 602 will write at eachlocation. In some embodiments, block 824 includes instructions to stepthrough each of the locations or points that were determined at block804 and evaluate each point individually. In other embodiments, block824 may include instructions to evaluate more than one point at a timeto determine how many tips will write at that point. At block 826, themethod 820 may execute instructions to modify the list of regions thatwas determined at block 804. For example, where block 824 determinesthat no tips will write at a particular point within the list, then theprocessor 610 a may execute instructions of 826 to remove those locationfrom the list. At block 828, the method 820 may execute instructions toassign a residence time for locations at which tips will write. In someembodiments, the residence time may equal:

T _(residence)=((T _(delay) +T _(dwell))×#active tips)+T _(safety)  Equation 1:

Returning to FIG. 8A, block 810 may execute instructions to display apattern of points 710 within the user interface 700. The pattern 710 mayinclude those points that the tip array 602 will write. In someembodiments, the pattern 710 may include a region of the image asdetermined at block 804. At block 812, the method 800 may executeinstructions to write the instruction set for the lithography system 600using the parameters and other data of the methods 800 and 820 and storethe set in the memory 610 b. In some embodiments, the instruction setincludes a .ppl file for the AFM 608, although the system 600 may useother types of file formats. At block 814, the method 800 may executeinstructions to load the instruction set into a memory (i.e., memory 610b or a memory of the AFM 608). At block 816, the method 800 may executeinstructions to write the image 702 beginning with a pattern 710. Insome embodiments, the method 700 begins the writing process in responseto receiving a command from the user interface indicating selection of a“write” button 712 or other user-initiated command. In otherembodiments, the write process begins automatically upon generating theinstruction set or other action.

With reference to FIG. 8C, a method 840 may include instructions towrite the image 702 on a substrate. At block 842, the system 600 mayexecute instructions to move to a first location or “patterningposition” with the z-piezo of the array 602 lifted. For example, the tiparray may be lowered to be adjacent to the substrate, but not contactingthe substrate or can be contacting the substrate depending on thedesired feature size. Once at the first location, block 844 may executeinstructions to lower the z-piezo to a descended position over thesubstrate. At block 846, the method 840 may execute instructions tomonitor the threshold voltage (i.e., the z-piezo voltage) to determineif the z-piezo is extended. For example, the z-piezo is indicative ofthe vertical position of the tip array relative to the substrate. Insome embodiments, the method 840 instructs the DAQ 612 to monitor thez-piezo voltage and determine, at block 848, whether the z-piezo hasexceeded a trigger voltage (i.e., one of the parameters entered at block806). The threshold or z-piezo voltage is indicative of the tip arraybeing in the patterning position. If, at block 848, the method 840determines that the trigger voltage is exceeded (and, thus, the z-piezois extended), then the method 840 may activate one or more tips of thearray 602 to begin a projecting/writing process for a first region ofthe image 702. The activated tips may continue the projecting/writingprocess for the duration of the dwell time. In some embodiments, themethod may load a next geometric region for the lithography process ifthe dwell time exceeds a threshold amount (e.g., 1.45 seconds). Further,block 850 may include instructions to wait a period of time (e.g., thewait time) before lifting the z-piezo away from the substrate and movingto a second geometric region of the image 702.

With reference to FIG. 8D, each tip of the array 602 may be activatedone at a time. At block 862, the method 860 may execute instructions toset a voltage to high for a particular tip corresponding to the region710. For example, the method 860 may instruct the system 600 to set avoltage to “high” for a tip which, at block 864, switches a transistor(i.e., an NPN transistor) to allow current to pass though a heater forthe selected tip within the array 602. This voltage may be set to “high”for a variable amount of time corresponding to one of the parametersentered at block 806 (e.g., a dwell time). At the expiration of thedwell time, the high voltage for the tip may be set to zero at block866. At block 868, the method 860 may determine if another tip at theregion 710 should write and, if so, proceed to block 362. If there areno more tips for the writing process at the region 710, then the method860 may end. Returning to FIG. 8C, following writing the entire region710, the method 840 may execute instructions to determine if the image702 includes another region at block 852. If the image 702 includesanother region 710, then block 852 may cause the method 840 to executeinstructions to lift the z-piezo of the array and travel to the nextregion. If the image 702 does not include another region 710, then block852 may cause the method 840 to return to method 300 and end.

Computing System for Implementing the Methods

FIG. 9 is a high-level block diagram of an example computing environmentfor a lithography system to execute the methods as herein described. Thecomputing device 901 may include any of the computing devices describedherein (e.g., a desktop or laptop computer, a tablet computer, aWi-Fi-enabled device or other personal computing device capable ofwireless or wired communication), a thin client, or other known type ofcomputing device. As will be recognized by one skilled in the art, inlight of the disclosure and teachings herein, other types of computingdevices can be used that have different architectures. Processor systemssimilar or identical to the example lithography systems 100, 500, and600 may be used to implement and execute the example system of FIG. 1,the example methods, the user interfaces, and the like. Although theexample systems are described as including a plurality of peripherals,interfaces, chips, memories, etc., one or more of those elements may beomitted from other example processor systems used to implement andexecute the example systems. Also, other components may be added.

As shown in FIG. 9, the computing device 901 of this embodiment includesa processor 902 that is coupled to an interconnection bus 904. Theprocessor 902 includes a register set or register space 906, which isdepicted in FIG. 9 as being entirely on-chip, but which couldalternatively be located entirely or partially off-chip and directlycoupled to the processor 902 via dedicated electrical connections and/orvia the interconnection bus 904. The processor 902 may be any suitableprocessor, processing unit or microprocessor. Although not shown in FIG.9, the computing device 901 may be a multi-processor device and, thus,may include one or more additional processors that are identical orsimilar to the processor 902 and that are communicatively coupled to theinterconnection bus 904.

The processor 902 of FIG. 9 is coupled to a chipset 908, which includesa memory controller 910 and a peripheral input/output (I/O) controller912. As is well known, a chipset typically provides I/O and memorymanagement functions as well as a plurality of general purpose and/orspecial purpose registers, timers, etc. that are accessible or used byone or more processors coupled to the chipset 908. The memory controller910 performs functions that enable the processor 902 (or processors ifthere are multiple processors) to access a system memory 914 and a massstorage memory 916.

The system memory 914 may include any desired type of volatile and/ornon-volatile memory such as, for example, static random access memory(SRAM), dynamic random access memory (DRAM), flash memory, read-onlymemory (ROM), etc. The mass storage memory 916 may include any desiredtype of mass storage device. For example, if the computing device 901 isused to implement a module 918 having an application programminginterface (API) 919 (including functions and instructions as describedby the methods of FIGS. 2b -d, 4, 8 a-d), and user interfaces (UI) 200,300, and 700 to receive user input, the mass storage memory 916 mayinclude a hard disk drive, an optical drive, a tape storage device, asolid-state memory (e.g., a flash memory, a RAM memory, etc.), amagnetic memory (e.g., a hard drive), or any other memory suitable formass storage. In one embodiment, non-transitory program functions,modules and routines (e.g., an application 918, an API 920, and the userinterfaces, etc.) are stored in mass storage memory 916, loaded intosystem memory 914, and executed by a processor 902 or can be providedfrom computer program products that are stored in tangiblecomputer-readable storage mediums (e.g. RAM, hard disk, optical/magneticmedia, etc.). Mass storage 916 may also include a cache memory 921storing application data, user profile data, and timestamp datacorresponding to the application data, and other data for use by theapplication 918.

The peripheral I/O controller 910 performs functions that enable theprocessor 902 to communicate with peripheral input/output (I/O) devices922 and 924, a network interface 926, via a peripheral I/O bus 928. TheI/O devices 922 and 924 may be any desired type of I/O device such as,for example, a keyboard, a display (e.g., a liquid crystal display(LCD), a cathode ray tube (CRT) display, etc.), a navigation device(e.g., a mouse, a trackball, a capacitive touch pad, a joystick, etc.),etc. The I/O devices 922 and 924 may be used with the application 918 toprovide an instruction set and the user interfaces as described inrelation to the figures. The local network transceiver 928 may includesupport for Wi-Fi network, Bluetooth, Infrared, cellular, or otherwireless data transmission protocols. In other embodiments, one elementmay simultaneously support each of the various wireless protocolsemployed by the computing device 901. For example, a software-definedradio may be able to support multiple protocols via downloadableinstructions. In operation, the computing device 901 may be able toperiodically poll for visible wireless network transmitters (bothcellular and local network) on a periodic basis. Such polling may bepossible even while normal wireless traffic is being supported on thecomputing device 901. The network interface 926 may be, for example, anEthernet device, an asynchronous transfer mode (ATM) device, an 802.11wireless interface device, a DSL modem, a cable modem, a cellular modem,etc., that enables the systems 100, 500, and 600 to communicate withanother computer system having at least the elements described inrelation to the systems.

While the memory controller 912 and the I/O controller 910 are depictedin FIG. 9 as separate functional blocks within the chipset 908, thefunctions performed by these blocks may be integrated within a singleintegrated circuit or may be implemented using two or more separateintegrated circuits. The systems 100, 500, and 600 may also implementthe user interfaces and instruction sets on remote computing devices 930and 932. The remote computing devices 930 and 932 may communicate withthe computing device 901 over a network link 934. For example, thecomputing device 901 may receive location data created by an applicationexecuting on a remote computing device 930, 932. In some embodiments,the module 918 including the user interfaces may be retrieved by thecomputing device 901 from a cloud computing server 936 via the Internet938. When using the cloud computing server 936, the module 918 may beprogrammatically linked with the computing device 901. The module 918may be a Java® applet executing within a Java® Virtual Machine (JVM)environment resident in the computing device 901 or the remote computingdevices 930, 932. The module 918 may also be a “plug-in” adapted toexecute in a web-browser located on the computing devices 901, 930, and932. In some embodiments, the module 918 may communicate with back endcomponents via the Internet or other type of network.

Tip Arrays Polymer Pen and Gel Pen Tip Arrays

Polymer Pen Lithography is a direct-write method that deliverscollections of molecules in a positive printing mode. Polymer PenLithography utilizes elastomeric tips without cantilevers as the inkdelivery tool. The tips are preferably made of polydimethylsiloxane,PDMS or agarose gel. As used herein, “Gel Polymer Pen Lithography” and“Gel Pen Lithography” refer to Polymer Pen Lithography utilizingelastomeric gel polymer tips. Reference to Polymer Pen Lithography orpolymer pen tip arrays herein should be understood to include Gel PenLithography and Gel Pen tip arrays. As used herein, references topolymers, polymer pens, and polymer pen tip arrays include gel polymertypes, unless indicated otherwise in context.

A preferred polymer pen tip array (FIG. 16) contains thousands of tips,preferably having a pyramidal shape, which can be made with a masterprepared by conventional photolithography and subsequent wet chemicaletching (FIGS. 16a and 17). The tips preferably are connected by acommon substrate which includes a thin polymer backing layer (50-100 μmthick), which preferably is adhered to a rigid support (e.g., a glass,silicon, quartz, ceramic, polymer, or any combination thereof), e.g.prior to or via curing of the polymer. The rigid support is preferablyhighly rigid and has a highly planar surface upon which to mount thearray (e.g., silica glass, quartz, and the like). The rigid support andthin backing layer significantly improve the uniformity of the polymerpen tip array over large areas, such as three inch wafer surface (FIG.16B), and make possible the leveling and uniform, controlled use of thearray. When the sharp tips of the polymer pen tips are brought incontact with a substrate, ink is delivered at the points of contact(FIGS. 16a and 17). Gel pen lithography is a direct-write method thatdelivers collections of molecules in a positive printing mode. A gelpolymer can be selected (e.g. a polysaccharide gel, e.g. agarose gel)such that the ink solution is absorbed into the gel matrix of a gel tiparray.

The amount of light reflected from the internal surfaces of the tipsincreases significantly when the tips make contact with the substrate.Therefore, a translucent or transparent elastomer polymer tip arrayallows one to visually determine when all of the tips are in contactwith an underlying substrate, permitting one to address the otherwisedaunting task of leveling the array in an experimentally straightforwardmanner. Thus, preferably one or more of the array tips, backing layer,and rigid support are at least translucent, and preferably transparent.

Polymer pen or gel pen lithography can be performed, for example, withan Nscriptor™ system (NanoInk Inc., Ill.).

Referring to FIG. 17, an embodiment of a tip array 10 includes a tipsubstrate layer 12 and a plurality of tips 14 fixed to the tip substratelayer 12. The tip substrate layer 12 and the plurality of tips 14 areformed of a polymer and one or both can be formed of a transparentpolymer. The tip substrate layer 12 and the tips 14 can be formed of thesame polymer or can be formed of different polymers.

The tip substrate layer 12 can have any suitable thickness, for examplein a range of about 50 μm to about 5 mm, about 50 μm to about 100 μm, orabout 1 mm to about 5 mm. For example, the tip substrate layer 12 canhave a minimum thickness of about 50, 100, 200, 300, 400, 500, 600, 700,800, 900, 1000, 2000, 3000, 4000, or 5000 μm. For example, the tipsubstrate layer 12 can have a maximum thickness of about 50, 100, 200,300, 400, 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, or 5000 μm.The thickness of the tip substrate layer can be decreased as therigidity of the polymer used to form the tip substrate layer increases.For example, for a gel polymer (e.g., agarose), the tip substrate layercan have a thickness in a range of about 1 mm to about 5 mm. For other,more rigid, polymers (e.g., PDMS) the tip substrate layer can have athickness in a range of about 50 μm to about 100 μm, for example. Thecombined thickness of the tip substrate layer 12 and the tips 14 can bein range of about 50 μm to about 5 mm. For example, for a gel polymer(e.g., agarose), the combined thickness can be up to about 5 mm. Forexample, for other polymers (e.g., PDMS) the combined thickness can beless than about 200 μm, preferably less than about 150 μm, or morepreferably about 100 μm.

The tip substrate layer 12 can be attached to a transparent rigidsupport, for example, formed from glass, silicon, quartz, ceramic,polymer, or any combination thereof. The rigid support is preferablyhighly rigid and has a highly planar surface upon which to mount the tiparray 10.

The tip arrays are non-cantilevered and comprise tips 14 which can bedesigned to have any shape or spacing (pitch) between them, as needed.The shape of each tip can be the same or different from other tips 14 ofthe array, and preferably the tips 14 have a common shape. Contemplatedtip shapes include spheroid, hemispheroid, toroid, polyhedron, cone,cylinder, and pyramid (trigonal or square). The tips 14 have a baseportion fixed to the tip substrate layer 12. The base portion preferablyis larger than the tip end portion. The base portion can have an edgelength in a range of about 1 μm to about 50 μm, or about 5 μm to about50 μm. For example, the minimum edge length can be about 1, 2, 3, 4, 5,6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 22, 24, 26, 28,30, 32, 34, 36, 38, 40, 42, 44, 46, 48, or 50 μm. For example, themaximum edge length can be about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,13, 14, 15, 16, 17, 18, 19, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40,42, 44, 46, 48, or 50 μM.

A preferred tip array 10 contains thousands of tips 14, preferablyhaving a pyramidal shape. The substrate-contacting (tip end) portions ofthe tips 14 each can have a diameter in a range of about 50 nm to about1 μm before coating with the graphene film. For example, the minimumdiameter can be about 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 150,200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850,900, 950, or 1000 nm. For example, the minimum diameter can be about 50,55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 150, 200, 250, 300, 350, 400,450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, or 1000 nm. Thesubstrate-contacting portions of the tips 14 are preferably sharp, sothat each is suitable for forming submicron patterns, e.g., less thanabout 500 nm. The sharpness of the tip is measured by its radius ofcurvature. The tips 14 can have a radius of curvature before coatingwith the graphene film, for example, of below about 1 μm, and can beless than about 0.9 μm, less than about 0.8 μm, less than about 0.7 μm,less than about 0.6 μm, less than about 0.5 μm, less than about 0.4 μm,less than about 0.3 μm, less than about 0.2 μm, less than about 0.1 μm,less than about 90 nm, less than about 80 nm, less than about 70 nm,less than about 60 nm, or less than about 50 nm.

The tip-to-tip spacing between adjacent tips 14 (tip pitch) can be in arange of about 1 μm to about over 10 mm, or about 20 μm to about 1 mm.For example, the minimum tip-to-tip spacing can be about 1 μm, 2 μm, 3μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80μm, 85 μm, 90 μm, 95 μm, 100 μm, 200 μm, 300 m, 400 μm, 500 μm, 600 μm,700 μm, 800 μm, 900 μm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm,9 mm, or 10 mm. For example, the maximum tip-to-tip spacing can be about1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 200 μm, 300 m, 400 μm,500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6mm, 7 mm, 8 mm, 9 mm, or 10 mm.

The tips 14 of the tip array 10 can be designed to have any desiredthickness, for example in a range of about 50 nm to about 50 μm, about50 nm to about 1 μm, about 10 μm to about 50 μm, about 50 nm to about500 nm, about 50 nm to about 400 nm, about 50 nm to about 300 nm, about50 nm to about 200 nm, or about 50 nm to about 100 nm. For example, theminimum thickness can be about 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, or 50μm. For example, the maximum thickness can be about 50 nm, 60 nm, 70 nm,80 nm, 90 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm,800 nm, 900 nm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40μm, 45 μm, or 50 μm. The thickness of the tip array 10 can be decreasedas the rigidity of the polymer used to form the tip substrate layerincreases. For example, for a gel polymer (e.g., agarose), the tip array10 can have a thickness in a range of about 10 μm to about 50 μm. Forother polymers (e.g., PDMS), for example, the tip array 10 can have athickness of about 50 nm to about 1 μm. As used herein, the thickness ofthe tip array 10 refers to the distance from the tip end to the base endof a tip. The tips 14 can be arranged randomly or in a regular periodicpattern (e.g., in columns and rows, in a circular pattern, or the like).

Polymeric materials suitable for use in the tip array 10 can have linearor branched backbones, and can be crosslinked or non-crosslinked,depending upon the particular polymer and the degree of compressibilitydesired for the tip. Cross-linkers refer to multi-functional monomerscapable of forming two or more covalent bonds between polymer molecules.Non-limiting examples of cross-linkers include such astrimethylolpropane trimethacrylate (TMPTMA), divinylbenzene, di-epoxies,tri-epoxies, tetra-epoxies, di-vinyl ethers, tri-vinyl ethers,tetra-vinyl ethers, and combinations thereof.

Thermoplastic or thermosetting polymers can be used, as can crosslinkedelastomers. In general, the polymers can be porous and/or amorphous. Avariety of elastomeric polymeric materials are contemplated, includingpolymers of the general classes of silicone polymers and epoxy polymers.Polymers having low glass transition temperatures such as, for example,below 25° C. or more preferably below −50° C., can be used. Diglycidylethers of bisphenol A can be used, in addition to compounds based onaromatic amine, triazine, and cycloaliphatic backbones. Another exampleincludes Novolac polymers. Other contemplated elastomeric polymersinclude methylchlorosilanes, ethylchlorosilanes, andphenylchlorosilanes, polydimethylsiloxane (PDMS). Other materialsinclude polyethylene, polystyrene, polybutadiene, polyurethane,polyisoprene, polyacrylic rubber, fluorosilicone rubber, andfluoroelastomers.

Further examples of suitable polymers that may be used to form a tip canbe found in U.S. Pat. No. 5,776,748; U.S. Pat. No. 6,596,346; and U.S.Pat. No. 6,500,549, each of which is hereby incorporated by reference inits entirety. Other suitable polymers include those disclosed by He etal., Langmuir 2003, 19, 6982-6986; Donzel et al., Adv. Mater. 2001, 13,1164-1167; and Martin et al., Langmuir, 1998, 14-15, 3791-3795.Hydrophobic polymers such as polydimethylsiloxane can be modified eitherchemically or physically by, for example, exposure to a solution of astrong oxidizer or to an oxygen plasma.

The polymer of the tip array 10 can be a polymer gel. The gel polymercan comprise any suitable gel, including hydrogels and organogels. Forexample, the polymer gel can be a silicon hydrogel, a branchedpolysaccharide gel, an unbranched polysaccharide gel, a polyacrylamidegel, a polyethylene oxide gel, a cross-linked polyethylene oxide gel, apoly(2-acrylamido-2-methyl-1-propanesulfonic acid) (polyAMPS) gel, apolyvinylpyrrolidone gel, a cross-linked polyvinylpyrrolidone gel, amethylcellulose gel, a hyaluronan gel, and combinations thereof. Forexample, the polymer gel can be an agarose gel. By weight, gels aremostly liquid, for example the gel can be greater than 95% liquid, yetbehave like a solid due to the presence of a cross-linked network withinthe liquid.

The material used to form the tip array 10 has a suitable compressionmodulus and surface hardness to prevent collapse of the tip duringcontact with the surface, but too high a modulus and too great a surfacehardness can lead to a brittle material that cannot adapt and conform toa substrate surface during exposure. As disclosed in Schmid, et al.,Macromolecules, 33:3042 (2000), vinyl and hydrosilane prepolymers can betailored to provide polymers of different modulus and surface hardness.Thus, in another type of embodiment, the polymer can be a mixture ofvinyl and hydrosilane prepolymers, wherein the weight ratio of vinylprepolymer to hydrosilane crosslinker is about 5:1 to about 20:1, about7:1 to about 15:1, or about 8:1 to about 12:1.

The material used to form the tip array 10 can have a surface hardnessof about 0.2% to about 3.5% of glass, as measured by resistance of asurface to penetration by a hard sphere with a diameter of 1 mm,compared to the resistance of a glass surface (as described in Schmid,et al., Macromolecules, 33:3042 (2000) at p 3044). The surface hardnessoptionally can be about 0.3% to about 3.3%, about 0.4% to about 3.2%,about 0.5% to about 3.0%, or about 0.7% to about 2.7% of glass. Thepolymers of the tip array 10 can have a compression modulus of about 10MPa to about 300 MPa. The tip array 10 preferably comprises acompressible polymer which is Hookean under pressures of about 10 MPa toabout 300 MPa. The linear relationship between pressure exerted on thetip array 10 and the feature size allows for control of the near fieldand feature size using the disclosed methods and tip arrays.

A Polymer Pen Lithography tip array can comprise a polymer that hasadsorption and/or absorption properties for the patterning composition,such that the tip array acts as its own patterning compositionreservoir. For example, PDMS is known to adsorb patterning inks. Seee.g., U.S. Patent Publication No 2004/22962, Zhang et al., Nano Lett. 4,1649 (2004), and Wang et al., Langmuir 19, 8951 (2003).

Polymer Pen Lithography tip arrays can be made with a master prepared byconventional photolithography and subsequent wet chemical etching. Themold can be engineered to contain as many tips arrayed in any fashiondesired. The tips of the tip array can be any number desired, andcontemplated numbers of tips 14 include about 1000 tips 14 to about 15million tips, or greater. The number of tips 14 of the tip array 10 canbe greater than about 1 million, greater than about 2 million, greaterthan about 3 million, greater than about 4 million, greater than 5million tips 14, greater than 6 million, greater than 7 million, greaterthan 8 million, greater than 9 million, greater than 10 million, greaterthan 11 million, greater than 12 million, greater than 13 million,greater than 14 million, or greater than 15 million tips.

Polymer Pen Lithography exhibits both time- and pressure-dependent inktransport. Polymer Pen Lithography probes having a graphene film coatedthereon also exhibit both time- and pressure-dependent ink transport.This property of Polymer Pen Lithography, which is a result of thediffusive characteristics of the ink and the small size of the deliverytips, allows one to pattern sub-micron features with high precision andreproducibility (variation of feature size is less than 10% under thesame experimental conditions). The pressure dependence of Polymer PenLithography derives from the compressible nature of the elastomerpyramid array and is not inhibited by the graphene film. Indeed, themicroscopic, preferably pyramidal, tips can be made to deform withsuccessively increasing amounts of applied pressure, which can becontrolled by simply extending the piezo in the vertical direction(z-piezo). The controlled deformation can be used as an adjustablevariable, allowing one to control tip-substrate contact area andresulting feature size. Within the pressure range allowed by z-piezoextension of about 5 to about 25 μm, one can observe a near linearrelationship between piezo extension and feature size at a fixed contacttime of 1 s (FIG. 18). Interestingly, at the point of initial contactand up to a relative extension 0.5 μm, the sizes of the MHA dots do notsignificantly differ and are both about 500 nm, indicating that thebacking elastomer layer, which connects all of the pyramids, deformsbefore the pyramid-shaped tips do. This type of buffering is fortuitousand essential for leveling because it provides extra tolerance inbringing all of the tips in contact with the surface without tipdeformation and significantly changing the intended feature size. Whenthe z-piezo extends 1 μm or more, the tips exhibit a significant andcontrollable deformation (FIG. 3). With the pressure dependency ofPolymer Pen Lithography, one does not have to rely on thetime-consuming, meniscus-mediated ink diffusion process to generatelarge features. Indeed, one can generate either nanometer or micrometersized features in only one printing cycle by simply adjusting the degreeof tip deformation.

Polymer Pen Lithography allows for the combinatorial patterning ofmolecule-based and solid-state features with dynamic control overfeatures size, spacing, and shape. The maskless nature of Polymer PenLithography allows one to arbitrarily make many types of structureswithout the hurdle of designing a new master via a throughput-impededserial process. In addition, Polymer Pen Lithography can be used withsub-100 nm resolution with the registration capabilities of aclosed-loop scanner.

Beam Pen Lithography

The tips 14 of a Beam Pen Lithography tip array can be used to bothchannel the radiation to a surface in a massively parallel scanningprobe lithographic process and to control one or more parameters such asthe distance between the tip and the substrate, and the degree of tipdeformation. Control of such parameters can allow one to take advantageof near-field effects. In one embodiment, the tips 14 are elastomericand reversibly deformable, which can allow the tip array 10 to bebrought in contact with the substrate without damage to the substrate orthe tip array 10. This contact can ensure the generation of near-fieldeffects.

Referring to FIGS. 4, an embodiment of a Beam Pen Lithography tip array10 includes a tip substrate layer 12 and a plurality of tips 14 fixed tothe tip substrate layer 12. The tip substrate layer 12 and the pluralityof tips 14 are formed of a transparent polymer. The tip substrate layer12 and the tips 14 can be formed of the same polymer or can be formed ofdifferent polymers. Details regarding the tips and tip arrays,including, for example, the tip and tip substrate dimensions, shape,spacing, materials, and number of tips, are provided above.

A Beam Pen Lithograph tip array 10 further includes a blocking layer 16coated on the sidewalls of the tips 14 and on the portions of the tipsubstrate layer 12 between adjacent tips 14. Referring to FIG. 19, anaperture 18 is defined in the blocking layer 16 at the tip end (e.g.,the photosensitive layer-contacting end of each of the tips 14), suchthat the transparent polymer tip end is exposed through the aperture 18.The tips 14 are formed from a material which is at least translucent tothe wavelength of radiation intended for use in patterning, e.g. in arange of 300 nm to 600 nm, and preferably the tips 14 are transparent tosuch light. Each tip can have a blocking layer 16 disposed thereon, withan aperture 18 defined in the blocking layer 16 and exposing the tipend. The blocking layer 16 serves as a radiation blocking layer 16,channeling the radiation through the material of the tip and out theexposed tip end.

The blocking layer 16 on the polymer tip sidewalls serves as a radiationblocking layer 16, allowing the radiation illuminated on a surface ofthe substrate layer opposite the surface to which the tips 14 are fixedto be emitted only through the tip end exposed by the aperture 18defined in the blocking layer 16. The exposure of a substrate pre-coatedwith a resist layer 20 with the radiation channeled through the tip ends18 of the tip array 10 can allow for the formation of a single dot pertip for each exposure. The blocking layer 16 can be formed of anymaterial suitable for blocking (e.g., reflecting) a type of radiationused in the lithography process. For example, the blocking layer 16 canbe a metal, such as gold, when used with UV light. Other suitableblocking layers include, but are not limited to, gold, chromium,titanium, silver, copper, nickel, silicon, aluminum, opaque organicmolecules and polymers, and combinations thereof. The blocking layer 16can have any suitable thickness, for example in a range of about 40 nmto about 500 nm. For example, the minimum thickness can be about 40, 45,50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 150, 200, 250, 300, 350,400, 450, or 500 nm. For example, the maximum thickness can be about 40,45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 150, 200, 250, 300,350, 400, 450, or 500 nm.

The pressure dependence exhibited by polymer pen lithography tip arraysand described above is similarly exhibited by beam pen lithography tiparrays. As noted above, the graphene film does not inhibit or otherwiseadversely affect the pressure dependent properties of beam penlithography.

As described above, the tip portion of the tip arrays can be made with amaster prepared by conventional photolithography and subsequent wetchemical etching. The mold can be engineered to contain as many tips 14arrayed in any fashion desired. The tips of the tip array can be anynumber desired, and contemplated numbers of tips 14 include about 1000tips 14 to about 15 million tips, or greater. The number of tips 14 ofthe tip array 10 can be greater than about 1 million, greater than about2 million, greater than about 3 million, greater than about 4 million,greater than 5 million tips 14, greater than 6 million, greater than 7million, greater than 8 million, greater than 9 million, greater than 10million, greater than 11 million, greater than 12 million, greater than13 million, greater than 14 million, or greater than 15 million tips.

Optionally, the tips 14 can be cleaned, for example, using oxygenplasma, prior to coating with the blocking layer 16. The blocking layer16 can be disposed on the tips 14 by any suitable process, includingcoating, for example, spin-coating, the tips 14 with the blocking layer16

An aperture 18 in the blocking layer 16 can be formed by any suitablemethod, including, for example, focused ion beam (FIB) methods, dry andwet chemical etchings, or using a lift-off method. The lift-off methodcan be a dry lift off method. Referring to FIG. 6A, one suitableapproach includes applying an adhesive 22, such as poly(methylmethacrylate) (PMMA) on top of the blocking layer 16 of the tip array10, and removing a portion of the adhesive 22 material disposed at thesubstrate contacting end of the tips 14 by contacting the tip array 10to a clean and flat surface, for example a glass surface. The tips 14can then be immersed in an etching solution to remove the exposedportion of the blocking layer 16 to form the aperture 18 and expose thematerial of the tip, e.g. the transparent polymer. The remainingadhesive 22 material protects the covered surfaces of the blocking layer16 from being etched during the etching step. The adhesive can be, forexample, PMMA, poly(ethylene glycol) (PEG), polyacrylonitrile, andcombinations thereof.

Referring to FIGS. 21B and 26, alternatively, a simple contact approachcan be used in which a tip array 10 having the blocking layer 16 isbrought in contact with a glass slide or other surface coated with anadhesive 22 material, such as PMMA. Other suitable adhesive 22 materialsinclude, for example, PMMA, PEG, polyacrylonitrile, and combinationsthereof. Upon removal of the pen tip from surface coated with theadhesive 22 material, the adhesive 22 material removes the contactedportion of the blocking layer 16, thereby defining an aperture 18 andexposing the tip material, e.g. the transparent polymer.

In either of the above described aperture 18 forming methods, the sizeof the aperture 18 formed can be controlled by applying differentexternal forces on the backside of the BPL tip array 10. As a result ofthe flexibility of elastomeric tips 14, the application of force on thebackside of the BPL tip array 10 can be used to control the contact areabetween the tips 14 and adhesive 22 material surface. The contact forceoptionally can be in a range of about 0.002 N to about 0.2N for a 1 cm²tip array.

Referring to FIG. 26, in an embodiment, the aperture is formed bycoating the tip array having the blocking layer with a polymer layer,such as a layer of PMMA. The tip array can be repeatedly coated with thepolymer layer to ensure complete coverage of the tips. The polymer layercan be coated on the blocking layer, for example, using spin coating orany other suitable coating methods, as is well known in the art.Reactive ion etching can then be used to etch the polymer layer andexpose the apexes of the tips. The reactive ion etching process can bemonitored, for example, using optical microscopy to ensure that etchingis stopped when only the apexes are exposed or to ensure the desiredamount of etching be done to form a selected aperture size. The size ofthe aperture can be controlled by controlling the etching of the polymerlayer to expose more or less of the apex of the tip. The blocking layerexposed through the etched portion of the polymer layer can then beetched using any known etching process, for example, a chemical etchingprocess, and using the remaining polymer layer as an etch mask. Theexposed blocking layer can be etched to expose the underlying polymerlayer of the tips and thereby form the aperture. The polymer layer canbe removed using any suitable methods. For example, the polymer layercan be removed by rinsing with acetone.

Any of the above-described approaches can be utilized when forming ablocking layer on a tip having a graphene film coated thereon.

The BPL tip array 10 can include pyramidal tips 14, with eachpyramid-shaped tip being covered by a gold blocking layer 16 having asmall aperture 18 defined in the blocking layer 16 at the very end ofthe tip. The size of the aperture 18 does not significantly change fromtip to tip. For example, the size of the aperture 18 can vary less thanabout 10% from tip to tip. The size of the aperture 18 can be tailoredover the 200 nm to 1 to 10 μm ranges, for example, by controllingcontact force. For example, the aperture 18 can have a diameter in arange of about 5 nm to about 5 μm, about 30 nm to about 500 nm, or about200 nm to about 5 μm. For example, the minimum aperture 18 diameter canbe about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80,85, 90, 95, 100, 200, 300, 400, 500, 600, 700, 800, 900 1000, 1500,2000, 2500, 3000, 3500, 4000, 4500, or 5000 nm. For example, the maximumaperture 18 diameter can be about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50,55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 200, 300, 400, 500, 600, 700,800, 900 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, or 5000 nm.

A PDMS array of pyramid-shape tips 14 can be fabricated by knownmethods. (17, 20). For example, each pyramid tip can have a square basewith a several tens of μm edge length and can come to a tip that has tipdiameter of about 100 nm. The entire array, including tips 14, can thenbe cleaned, for example, by oxygen plasma and covered with a blockinglayer 16 (e.g. gold), by a thermal evaporation method, for example. Thecoating can include, for example, a layer of gold that is about 80 nmthick with an about 5 nm thick Ti adhesion layer. The tip array 10 isthen brought in contact with a glass slide coated with PMMA, an adhesive22 material, which subsequently removes the Au/Ti layer from the PDMStips 14 and exposes the underlying transparent PDMS.

In one class of embodiments, the graphene film is coated on the tipsprior to forming the blocking layer. In such embodiments, the graphenefilm is transparent and therefore can remain on the tip end withoutinhibiting the photolithography performance of the beam tip array. Inanother class of embodiments, the blocking layer is formed on the tipsand the graphene film is coated on the blocking layer. In suchembodiments, the aperture can be formed prior to forming the graphenefilm and the graphene film can be coated over the blocking layer and theaperture.

Hard Tip Soft Spring Lithography

Referring to FIGS. 22A and 22B, Hard tip soft spring lithography is amassively parallel, hybrid tip-based molecular printing method. Whensilicon is used for the tip material, Hard tip soft spring lithographyis also referred to as Silicon Pen Lithography. The method and apparatusemploys an array of tips, e.g. Si tips, mounted onto a backing layer tocreate patterns of molecules on surfaces with features as small as 30 nmin diameter over large area. While the tips described herein aredescribed in the context of silicon or silicon-containing tips, the tipscan also comprise a metal, metalloid, a semi-conducing material, and/orcombinations thereof. For example, silicon nitride AFM probes, metalcarbide coated AFM probes, plasma treated AFM probes, silanized AFMprobes, diamond AFM probes, gallium containing materials (e.g., galliumnitride, gallium sulfide, gallium arsenide), and other semi-conductingmaterials are known in the art. The tips can have an average radius ofcurvature of, e.g., down to 22 nm or even less. Hard tip soft springlithography tips arrays demonstrate time-dependent feature size that isanalogous to DPN, but there is no relation between the force and thefeature size, which is distinct from polymer pen lithography. Hard tipsoft spring lithography tips can write features as small as 34 nm, andcan transfer energy to the surface to form a pattern.

The tip arrays disclosed herein comprise a plurality of tips (e.g.,silicon or silicon-containing) fixed to an elastomeric backing layer.The backing layer can be at least translucent, or preferablysubstantially transparent. The backing layer can have any suitablethickness, for example in a range of about 50 μm to about 1000 μm, about50 μm to about 500 μm, about 50 μm to about 250 μm, or about 50 μm toabout 200 μm, or about 50 μm to about 100 μm.

The elastomeric backing layer comprises an elastomeric polymericmaterial. Polymeric materials suitable for use in the backing layer canhave linear or branched backbones, and can be crosslinked ornon-crosslinked. Cross-linkers refer to multi-functional monomerscapable of forming two or more covalent bonds between polymer molecules.Non-limiting examples of cross-linkers include such astrimethylolpropane trimethacrylate (TMPTMA), divinylbenzene, di-epoxies,tri-epoxies, tetra-epoxies, di-vinyl ethers, tri-vinyl ethers,tetra-vinyl ethers, and combinations thereof.

Thermoplastic or thermosetting polymers can be used, as can crosslinkedelastomers. In general, the polymers can be porous and/or amorphous. Avariety of elastomeric polymeric materials are contemplated, includingpolymers of the general classes of silicone polymers and epoxy polymers.Polymers having low glass transition temperatures such as, for example,below 25° C. or more preferably below −50° C., can be used. Diglycidylethers of bisphenol A can be used, in addition to compounds based onaromatic amine, triazine, and cycloaliphatic backbones. Another exampleincludes Novolac polymers. Other contemplated elastomeric polymersinclude methylchlorosilanes, ethylchlorosilanes, andphenylchlorosilanes, polydimethylsiloxane (PDMS). Other materialsinclude polyethylene, polystyrene, polybutadiene, polyurethane,polyisoprene, polyacrylic rubber, fluorosilicone rubber, andfluoroelastomers.

Further examples of suitable polymers that may be used in the backinglayer can be found in U.S. Pat. No. 5,776,748; U.S. Pat. No. 6,596,346;and U.S. Pat. No. 6,500,549, each of which is hereby incorporated byreference in its entirety. Other suitable polymers include thosedisclosed by He et al., Langmuir 2003, 19, 6982-6986; Donzel et al.,Adv. Mater. 2001, 13, 1164-1167; and Martin et al., Langmuir, 1998,14-15, 3791-3795. Hydrophobic polymers such as polydimethylsiloxane canbe modified either chemically or physically by, for example, exposure toa solution of a strong oxidizer or to an oxygen plasma. In some cases,the elastomeric polymer is a mixture of vinyl and hydrosilaneprepolymers, where the weight ratio of vinyl prepolymer to hydrosilanecrosslinker is about 5:1 to about 20:1, about 7:1 to about 15:1, orabout 8:1 to about 12:1.

The tips of the tip array can be any number desired, and contemplatednumbers of tips include about 100 tips to about 15 million tips, orgreater. The number of tips of the tip array can be greater than about 1million, greater than about 2 million, greater than about 3 million,greater than about 4 million, greater than 5 million tips, greater than6 million, greater than 7 million, greater than 8 million, greater than9 million, greater than 10 million, greater than 11 million, greaterthan 12 million, greater than 13 million, greater than 14 million, orgreater than 15 million tips.

The tip array comprising tips and backing layer can have any suitablethickness, for example in a range of about 50 μm to about 5 mm, about 50μm to about 100 μm, or about 1 mm to about 5 mm. For example, the tiparray can have a minimum thickness of about 50, 100, 200, 300, 400, 500,600, 700, 800, 900, 1000, 2000, 3000, 4000, or 5000 μm. For example, thebacking layer can have a maximum thickness of about 50, 100, 200, 300,400, 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, or 5000 μm.

The tip array can be attached to a rigid support. The rigid support,when present, is disposed opposite the tips of the tip array andparallel to the backing layer. In some cases, the rigid support is atleast translucent, or is substantially transparent. In some cases, thebacking layer and rigid support together are at least translucent or aresubstantially transparent. Non-limiting examples of rigid supportsinclude formed from glass, silicon, quartz, ceramic, polymer, or anycombination thereof. The rigid support is preferably highly rigid andhas a highly planar surface upon which to mount the tip array. Thecombined thickness of the tip array and optional rigid support can be ofany desired thickness, for example in range of about 50 μm to about 5mm. The combined thickness can be less than about 5 mm, less than 1 mm,less than about 750 μm, or less than about 500 μm, for example.

The tip arrays are non-cantilevered and comprise tips (e.g. silicon orsilicon-containing) which can be designed to have any shape or spacing(pitch) between them, as needed. The shape of each tip can be the sameor different from other tips of the array, and preferably the tips havea common shape. Contemplated tip shapes include spheroid, hemispheroid,toroid, polyhedron, cone, cylinder, and pyramid (e.g., trigonal orsquare or octagonal). The tips can be arranged randomly or preferably ina regular periodic pattern (e.g., in columns and rows, in a circularpattern, or the like).

The tips have a base portion fixed to the backing layer. The baseportion preferably is larger than the tip end portion. The base portionof the tips can have diameter of any suitable dimension, for example ina range of about 1 μm to about 50 μm, or about 5 μm to about 50 μm, orless than 100 μm, or less than 50 μm. For example, the minimum diameterof the base of the tips can be about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 17, 18, 19, 20 22, 24, 26, 28, 30, 32, 34, 36, 38,40, 42, 44, 46, 48, or 50 μm. For example, the maximum diameter of thebase of the tips can be about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,14, 15, 16, 17, 18, 19, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42,44, 46, 48, or 50 μm.

A preferred shape of the tips is pyramidal, more preferably octagonalpyramidal. The substrate-contacting (tip end) portions of the tips eachcan have a radius of curvature of any suitable dimension, for example ina range of about 5 nm to about 1 μm. For example, the minimum radius ofcurvature can be about 5, 10, 15, 20, 21, 22, 23, 24, 25, 26, 27, 28,29, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 150,200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850,900, 950, or 1000 nm. The substrate-contacting portions of the tips arepreferably sharp, so that each is suitable for forming submicronpatterns, e.g., a radius of curvature of less than about 500 nm, lessthan 100 nm, less than 50 nm, or less than 25 nm.

The tip-to-tip spacing between adjacent tips (tip pitch) can be of anydesired dimension, for example in a range of about 1 μm to about over 10mm, or about 20 μm to about 1 mm. For example, the minimum tip-to-tipspacing can be about 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 200μm, 300 m, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1 mm, 2 mm, 3mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm. For example, themaximum tip-to-tip spacing can be about 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6μm, 7 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm,45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95μm, 100 μm, 200 μm, 300 m, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900μm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm.

The tips of the tip array can be designed to have any desired height,for example in a range of about 50 nm to less than 100 μm, about 50 nmto about 90 μm, about 50 nm to about 80 μm, about 50 nm to about 70 μm,about 50 nm to about 60 μm, about 10 μm to about 50 μm, about 50 nm toabout 40 μm, about 50 nm to about 30 μm, about 50 nm to about 20 μm,about 50 nm to about 500 nm, about 50 nm to about 400 nm, about 50 nm toabout 300 nm, about 50 nm to about 200 nm, or about 50 nm to about 100nm. For example, the minimum height can be about 50 nm, 60 nm, 70 nm, 80nm, 90 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800nm, 900 nm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm,45 μm, or 50 μm. For example, the maximum height can be about 50 nm, 60nm, 70 nm, 80 nm, 90 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm,700 nm, 800 nm, 900 nm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm,35 μm, 40 μm, 45 μm, or 100 μm.

The tip array can optionally include an adhesion-enhancing layer betweenthe tips and the backing layer. This layer can increase the stability ofthe tip-backing layer adhesion and/or increase the facility with whichthe tips and backing layer are adhered. The adhesion-enhancing layer canbe disposed over the entire elastomeric backing layer, or optionallyonly in selected regions (e.g. between each tip and the elastomericbacking layer). One non-limiting example of an adhesion-enhancing layeris a silicon dioxide layer. Other examples include epoxy resins or otheradhesive materials.

The tip array can optionally include a coating disposed on the exposedsurfaces of the tips and further optionally also over the surfaces ofthe backing layer adjacent to the tips. This coating can comprise aconductive material (e.g., a material capable of conducting electricalenergy), for example. Non-limiting examples of a conductive coatinginclude gold, silver, titanium, nickel, copper, conductive metals,conductive metal alloys, or combinations thereof.

The Si tips, prepared by a self-sharpening wet etching protocol, canhave a radius of curvature of about 22 nm, thereby enabling the easypreparation of sub-50 nm features in a pattern. Because the tip arrayscan be prepared on a glass slide, these arrays can be easily mountedonto the piezoelectric actuators of a conventional AFM, which providesthe precise tip positioning and registration that are hallmarks ofscanning probe lithographies. Both the elastomer and glass onto whichthe arrays are mounted can be selected to be transparent, which enablesthe compression of the elastomer that occurs when the tips touch thesurface of a substrate to be observed visually, thereby enabling astraightforward, optical method for leveling the plane of the tip arraywith respect to the substrate surface, when desired.

The preferred tip-array fabrication protocol described herein involvestwo major steps, photolithography and a self-sharpening etching step (22b). Importantly, no micromachining steps are required, thereby reducingsignificantly the manufacturing costs to about $10 for a 1×1 cm tiparray, whereas a single, cantilever-bound AFM probe costs about $40.Depending on the intended use, the pitch of a tip array can bedeliberately set between 100 and 200 μm, corresponding to tip densitiesof 10,000/cm2 and 2,500/cm2, respectively, and the density can be ashigh as 111,110/cm2 (9,007,700 tips in a 4-inch wafer) with a pitch of30 μm, for example.

The method can include the steps of providing a substrate wafer (e.g.,silicon) from which the tips will be formed; adhering an elastomericbacking layer to the wafer to form a structure; and etching the wafermaterial to form tips attached to the backing layer. Preferably, a maskpattern is formed over the wafer prior to etching, to form pre-tipregions.

As an example, to make the tip arrays, a Si wafer (e.g., 1×1 cm piece ofa 50 μm-thick (100)), optionally with a layer of silicon dioxide (SiO2)(e.g., 1 μm thick) on each side of the wafer, was placed onto uncuredelastomer. The top layer of SiO2 can serve as an etching mask material,while the SiO2 layer of the wafer in contact with the backing layer canincrease adhesion between the two surfaces, so that the tips do not falloff a certain PDMS elastomeric backing material once the wafer has beenetched (FIG. 23). Following an optional curing of elastomer of thebacking layer, an array of square SiO2 masks over silicon (e.g., pre-tipregions) are prepared from the top SiO2 layer along the <110> axis ofthe wafer by conventional photolithography and a subsequent bufferedhydrofluoric acid (HF) etch. The tips are prepared by etching the Si ofthe pre-tip regions and Si between pre-tip regions in an etchingsolution, e.g., 40% (w/v) aqueous potassium hydroxide (KOH) solutionthat etches the (311) and the (100) planes of the wafer at rates of 88and 50 μm/hr, respectively. In one preferred embodiment, during theetching, the Si wafer is embedded in the elastomer or backing layer(e.g., PDMS) so that the sides of the wafer are not exposed to theetching solution, thereby protecting the (110) crystal face exposed onthe sides that would etch faster than the (100) face on the surface. Inother embodiments, the sides of the wafer can be protected from etchantby any other suitable methods and materials, as would be recognized bythe skilled artisan. The sidewall etching rate, Rw/cos θ (θ is a slopeof sidewall), must exceed the surface etching rate, Rf in order to formsharp Si tips. Thus the anisotropy ratio η_(c) and the condition forself-sharpening points is expressed as η=R_(f)/R_(w)≦1/cos θ=η_(c),which indicates that faster etching rate for sidewall than that of flooris required to form a sharp tip. For (311) sidewall and (100) floor, theexperimental η=R₍₁₀₀₎/R₍₃₁₁₎ was measured as 0.56 in 40 wt % KOH at 70°C., while theoretical η_(c) is 3.33. This parameter can be changed toaltering the weight % of the KOH and/or the temperature at which theetching occurs. Other etching solutions that etch siliconanisotropically include ethylenediamine/pyrocathecol/water andtretramethylammonium hydroxide.

Analysis of the resulting tip arrays reveals that this fabricationprotocol does indeed achieve massively parallel Si tip arrays with tipradii of about 22 nm (FIG. 23E-23I). The massively parallel Si tip arrayis immobilized onto a glass slide (FIG. 23E), which is a rigid supportfor the arrays, allows handling of the fragile tip array without damage,and is a platform for mounting the arrays onto the AFM. In a preferredembodiment, the elastomeric backing and rigid support together aretransparent (FIG. 23F), which enables the visual leveling alignment ofthe tips onto a surface. A scanning electron microscope (SEM) image ofthe tips with 160 μm in pitch shows that the tips are remarkably uniformwith bottom width 30±0.6 μm, corresponding to a tip height of 47±0.9 μm,and that they adhere well to the elastomer surface (FIG. 23G). It wasfound by SEM that the surface intersection angles, α1, α2, and therotation of the intersection of the planes to the <100> plane of thewafer, φ, are 127.2, 143.3, and 18.3° (FIG. 23H), respectively, whichdemonstrates that the sidewall of the tips is (311) plane because thevalue of angles correspond perfectly to theoretical value of those for(311) of 126.9, 143.1, and 18.4°, respectively. Importantly, the Si tipradius of the arrays is found to be 22±3 nm (FIG. 23I), demonstratingthat self-sharpening has been achieved under the etching conditions of40% KOH in H2O. The tip radius can be reduced to 5 nm by changing theetching conditions, e.g., changing the KOH concentration and solutiontemperature during etching. This etching protocol, with a SiO2 etchingmask and homogeneous KOH etching provides a tip yield >99%. Since thewafer used in this experiment has a thickness variation of 10% (50±5 μm,NOVA Electronic Materials Ltd., Tex.), the tip height can vary up to10%.

In one exemplary embodiment, Hard tip soft spring lithography (HSL) tiparrays were formed using Si wafers (NOVA Electronic Materials;resistivity 1-10 Ω·cm, (100) orientation, 50±5 μm thick) with a 10,000-Å(±5%) SiO2 layer on each side were used for fabricating the tip arrays.The wafers were cleaned in acetone and ethanol, and then rinsed withwater before use. In preparing the elastomer base, PDMS and a curingagent (Sylgard 184 Silicone) were mixed in a 20:1 ratio (W/W), and thendegassed under vacuum (10-3 torr) for 30 minutes. Oxygen-plasma-treated(30 W at a pressure of 100 mTorr) wafers were then placed on drop-coatedPDMS on clean glass slides, followed by curing at 75° C. for 1 h. Beforecuring, the bubbles that can form at the interface between the wafer andthe uncured PDMS must be removed with additional degassing. To createHSL arrays, an array of squares must be defined on the surface of thesilicon wafer to act as etch masks. These squares must be between 120and 140 μm on edge (depending on the thickness of the silicon wafer) andthe edges of the squares and aligned along the Si layers <110>direction. This array of squares is created by photolithography thentransferred into the silica layer to form a hard mask for wet etching.The photolithography proceeds by treating with oxygen plasma for 1minute at 30 W, then spin coating photoresist (Shipley; S1805 positivephotoresist) at 500 r.p.m. for 10 s followed by 4,000 r.p.m. for 60 sonto the wafer/PDMS/glass slide. After spin-coating, the photoresist wasbaked at 105° C. for 90 s due to the thermal insulation of the PDMSlayer (on a conventional substrate this photoresist is usually baked foronly 60 s). The photoresist/wafer/PDMS/glass slide was exposed (UV lightsource) through a photomask defining the etch mask and subsequentlydeveloped (15 s, Shipley; Micoposit MF-319 Developer and washed withwater). The sample edge was passivated with PDMS to prevent etching infrom the sides. The exposed SiO2 was selectively etched in isotropicbuffered hydrofluoric acid (Transene, 9% HF, BUFFER-HF Improved) etchantfor 9 min in a polystyrene petri dish and then washed with water. Toremove the photoresist, the wafer was cleaned in acetone, ethanol, andsubsequently dried with flowing nitrogen. The wafer was then cleanedwith oxygen plasma (1 min at 30 W at a pressure of 100 mTorr). Oxygenplasma cleaning prior to Si etching was found to improve the uniformityof the tips. Samples were immediately transferred into 40 wt % KOH (333g KOH in 500 ml DI water) (KOH from Sigma-Aldrich; 99.99% metal basis,semiconductor grade, product no. 306568) at 75° C. and held in thecentre of the etchant in a Teflon holder. The solution was continuouslystirred to reduce the effect of micro-masking by hydrogen bubblesgenerated by the reaction at the Si surface. After 60-65 min, the samplewas removed from the etchant, was rinsed in water, rinsed in ethanol,and then dried in air. As the etching rate of Si(100) in 40 wt % KOH at75° C. is ˜50 μm·h-1, the minimum required thickness of SiO2 was foundto be 250 nm for an experimentally viable fabrication procedure, whichmotivated our choice for a 1 μm thick SiO2 layer.

Method of Coating the Tip Array with Graphene

Referring to FIG. 25A, in one embodiment of the disclosure, a microprobe having at least one tip is coated with a graphene film byimmersing the at least one tip in a fluid in which a graphene film isfloating on a surface thereof. The at least one tip can be immersedbeneath the floating graphene film and then the graphene film can bebrought into contact with the tip to thereby coat the tip. For example,the fluid can be evaporated to lower the graphene film into contact withthe at least one tip. Alternatively, the at least one tip can be raisedinto contact with the graphene film. In various embodiments in which themicro probe includes a plurality of tips, all or a subset of tips can beimmersed in the fluid to coat the immersed tips and immersed portions ofthe first side of the tip substrate layer with the graphene.

Optionally, prior to coating the tips can be cleaned or pre-treated. Inone embodiment, the tips are oxygen plasma treated.

The fluid can comprise water and a surfactant to lower the surfacetension of water. It has been advantageously found that a tentingphenomenon in which the graphene film tents over and does not conform tothe at least one tip can be avoided when the surface tension of thefluid (such as water) is reduced. When coating in water having nosurfactant a significant tenting phenomenon is observed, such that thegraphene layer covers across the tip ends and does not conform to thetips. By comparison, when a surfactant is added to the fluid to reducethe surface tension of the fluid, the tenting phenomenon is eliminated.Any suitable surfactant that is compatible and non-destructive tographene and the tip material, and optionally a backing support layer(e.g. polymethylmethacrylate (PMMA)), can be provided with the fluid forfloating graphene film. In one embodiment for use with water, thesurfactant is ethanol.

When immersed in the fluid, the tip or tip array can be angled relativeto the surface of the fluid (and, thus, the floating graphene film), asmeasured from a plane parallel to the base of the tip. It hasadvantageously been determined that tilting the tip or tip arrayimproves conformance of the graphene film to the tip or tip array.Referring to FIGS. 25A and 25B, tilting was advantageously found tomaximize the coating coverage. Furthermore, in embodiments in which atip array having a plurality of tips is coated, tilting of the tip arraycan allow for row by row coating of the tips with the graphene film asthe graphene film is brought into contact with the tip array. Theangling of the tip array also guides the graphene film across the tiparray as the successive rows are coated. The degree of tiling can bedependent upon by the tip-to-tip distances, tip bottom diameter, and thetip height (also referred to herein as tip thickness), and suitabledegrees can be determined through routine experimentation. For example,the tip or tip array can be tilted at least about 10° from the base ofthe tip, at least about 18°, at least about 20°, at least about 30°, orat least about 40° relative to the surface of the fluid. The angleoptionally can be in a range of about 10° to about 80°, about 20° toabout 70°, about 15° to about 60°, about 30° to about 60°, about 40° toabout 80°, about 20° to about 40°, about 10° to about 30°, about 15° toabout 45°, or about 25° to about 35°. Other suitable tilting anglesinclude, about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41,42, 43, 44, 45, 46, 47, 48, 49, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68,70, 72, 74, 76, 78, or 80°.

The graphene film can include one or more layers of graphene as notedabove. As used herein “graphene” refers to graphene as well aschemically- and electrochemically-modified graphene (e.g. covalent ornon-covalent modifications). The graphene film can further include asupport or backing layer when provided in the fluid. For example, thesupport layer can be PMMA. In embodiments in which the graphene film isprovided with a support layer, the support layer can be washed awayafter the graphene film is coated on the at least one tip. For example,when PMMA is used a support layer, acetone can be used to remove thePMMA layer after the tip is coated.

The graphene film provided in the fluid optionally can be larger in sizethan the tip or tip array to be coated. The portion of the graphenesheet extending beyond the tip or the tip array in such an arrangementcan be coated on a glass slide or cantilever supporting the tip or tiparray. Such excess coating can advantageously be used as electricalcontact points to electrically connect the graphene film and thereby thetip or tip array to a voltage source. This, in turn, can allow for asimple means of providing electro- or thermal-patterning functionalityto the tips.

As proof of concept, hard tip soft spring lithography tip arrays wereconformally coated with a multilayer film of graphene 20. In a typicalexperiment, 1×1 cm2 HSL tip arrays with 4,490 tips and a tip-to-tippitch of 150 μm were fabricated as described in paragraph 128 above.Large-area graphene films grown by chemical vapor deposition (CVD) on Nifilms (Graphene Laboratories Inc.) were used, and a thinpoly(methylmethacrylate) (PMMA) 22 (·70 nm) layer was spin coated on thegraphene, acting as a supporting layer for the graphene upon theseparation of the graphene from the Ni film. The PMMA/graphene wasseparated from the Ni film by etching away the Ni with a 1M FeCl3solution, and the PMMA/graphene was washed in DI water.

Following etching of the Ni film, the separated PMMA/graphene film wastransferred onto a HSL tip array (1×1 cm2) having silicon tips that hadbeen pre-treated with oxygen plasma. The transfer took place while thePMMA/graphene layer was floating on a mixture of water and ethanol (1:2V/V). The HSL tip array was submerged in the liquid and held at an angleof ˜40° with respect to the surface. The solvent was then allowed toevaporate, which caused the PMMA/graphene to fall onto the tip array andcoat it conformally.

Tilting the array during the solvent evaporation process significantlyimproved the coverage of graphene onto the tip array (FIG. 25B), whileutilizing a mixture of the water and ethanol reduced the surface tensionand improved the conformal coating (FIG. 13B). Subsequent washing withacetone was used to remove the PMMA. The graphene-coated,glass-supported tip arrays remained transparent, which allowed foroptical leveling of the tips with respect to a surface.

Low flexural rigidity also leads to surface wrinkles when a layerexperiences small compressive strain during the coating of a flatsurface. On further compression that can arise from coating an unevensurface, the wrinkles become unstable and new morphologies emerge,namely folds. Folds are observed between tips. This repetitive foldformation between the tips finally generates a network of folds thatcompletely connect tip to tip, thus indicating complete coverage of evenPMMA/graphene. Once the PMMA layer is removed, the flexural rigiditydecreases and the graphene experiences more mechanical sagging to thesurface. Indeed, as the network of folds formed by PMMA/graphene can beclearly seen, the graphene fold network can only be imaged by AFM and isnot clearly observable under an optical microscope. This excellentflexibility of graphene, which allows it to conform to the surface,leads to ultra-strong adhesion to the tip surface, owing to thegraphene's interaction with the surface being more liquid-like thansolid-like. Furthermore, the folds make the graphene layers more stableand resistant to mechanical stretching by making the layers moreexpandable, thus more coherently coupling the graphene to the tipsduring writing.

Beam Pent Lithography Patterning

In accordance with embodiments of the disclosure, projected lithographycan be used in connection with a beam pen tip array. Referring again toFIG. 19, beam pen lithography generally includes bringing a transparentpolymer tip array in contact with a photosensitive layer, for example,for example SHIPLEY1805 (MicroChem Inc.) photoresist material, followedby exposure (e.g. irradiation) of the top surface (the substrate layer)of the tip array 10 with a radiation source. The projected lithographysystem controls the exposure as described above. As a result of theblocking layer 16 blocking the radiation (e.g., by reflection), theradiation is transmitted through the transparent polymer and out theportion of the transparent polymer exposed by the aperture 18 (i.e., thetip end). Historically, photolithography has used ultraviolet light fromgas-discharge lamps using mercury, sometimes in combination with noblegases such as xenon. These lamps produce light across a broad spectrumwith several strong peaks in the ultraviolet range. This spectrum isfiltered to select a single spectral line, for example the “g-line” (436nm) or “i-line” (365 nm). More recently, lithography has moved to “deepultraviolet,” for example wavelengths below 300 nm, which can beproduced by excimer lasers. Krypton fluoride produces a 248-nm spectralline, and argon fluoride a 193-nm line. The type of radiation used withthe present apparatus and methods is not limited. One practicalconsideration is compatibility with the tip array materials. Radiationin the wavelength range of about 300 nm to about 600 nm is preferred,optionally 380 nm to 420 nm, for example about 365 nm, about 400 nm, orabout 436 nm. For example, the radiation optionally can have a minimumwavelength of about 300, 350, 400, 450, 500, 550, or 600 nm. Forexample, the radiation optionally can have a maximum wavelength of about300, 350, 400, 450, 500, 550, or 600 nm.

The photosensitive layer 20 can be exposed by the radiation transmittedthrough the polymer tip for any suitable time, for example in a range ofabout 1 second to about 1 minute. For example, the minimum exposure timecan be about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, or 60seconds. For example, the maximum exposure time can be about 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 20, 30, 40, 50, or 60 seconds.

The tip array 10 and/or the substrate can be moved during patterning toform the desired indicia. For example, in one embodiment, the tip array10 is moved while the substrate is held stationary. In anotherembodiment, the tip array 10 is held stationary while the substrate ismoved. In yet another embodiment, both the tip array 10 and thesubstrate are moved.

The method can further include developing the photosensitive layer 20,for example by any suitable process known in the art. For example, whena resist layer is used, the exposed resist layer can be developed for byexposed for about 30 seconds in MF319 (Rohm & Haas Electronic MaterialsLLC). The resist layer can be a positive resist or a negative resist. Ifa positive resist layer is used, developing of the resist layer 20removes the exposed portion of the resist layer. If a negative resistlayer is used, developing of the resist layer removes the unexposedportion of the resist layer.

Optionally, the method can further include depositing a patterning layeron the substrate surface after exposure followed by lift off of theresist layer to thereby form the patterning layer into the indiciaprinted on the resist layer by BPL. The patterning layer can be a metal,for example, and can be deposited, for example, by thermal evaporation.The resist lift off can be performed using, for example, acetone. Forexample, the patterns formed by pBPL can be developed for one minute inMF24A (MicroChem Inc., USA). The patterning layer can then be evaporatedonto the sample. For example, the patterning layer can be 5 nm of Cr and15 nm of Au. With such patterning compositions, an overnight lift-offprocedure can be performed, for example, in Remover PG (MicroChem Inc.,USA) to form the final patterns.

Another factor contributing to BPL resolution is the tip aperture 18size, which controls the area of the resist which is exposed to lightfrom the tip. Referring to FIG. 4A, with a near UV light or halogenlight source and conventional photolithography conditions, dot sizesclose to and below the light diffraction limit, of about 200 nm. Withoutintending to be bound by any particular theory, it is believed that thissmall feature size may be attributed to near-field effects at thepoint-of-contact between the tip and surface. Even though the aperture18 used to create a small, for example 200 nm dots can be 500 nm, thecontact area is much smaller, acting like a light pipe. Furtheroptimization of the photolithography conditions can include, forexample, using deep-UV illumination, thinner resist layers, and highresolution resist materials, which may improve BPL resolution down tothe sub-100 nm range.

The features that can be patterned range from sub-100 nm to 1 mm in sizeor greater, and can be controlled by altering the exposure time and/orthe contacting pressure of the tip array 10.

The BPL tip arrays can exhibit pressure dependence which results fromthe compressible nature of the polymer used to form the tip array 10.Indeed, the microscopic, preferably pyramidal, tips 14 can be made todeform with successively increasing amounts of applied pressure, whichcan be controlled by simply extending the piezo in the verticaldirection (z-piezo). The controlled deformation of the tip array 10 canbe used as an adjustable variable, allowing one to control tip-substratecontact area and resulting feature size. The pressure of the contact canbe controlled by the z-piezo of a piezo scanner. The more pressure (orforce) exerted on the tip array 10, the larger the feature size. Thus,any combination of contacting time and contacting force/pressure canprovide a means for the formation of a feature size from about 30 nm toabout 1 mm or greater. Within the pressure range allowed by z-piezoextension of about 5 to about 25 μm, one can observe a near linearrelationship between piezo extension and feature size at a fixed contacttime of 1 s. The substrate layer of the tip arrays can deform beforedeformation of the tips 14 occurs, which can offer a buffering providesextra tolerance in bringing all of the tips 14 in contact with thesurface without tip deformation and significantly changing the intendedfeature size. The contacting pressure of the tip array 10 can be about10 MPa to about 300 MPa.

At very low contact pressures, such as pressures of about 0.01 to about0.1 g/cm2 for the preferred materials described herein, the feature sizeof the resulting indicia is independent of the contacting pressure,which allows for one to level the tip array 10 on the substrate surfacewithout changing the feature size of the indicia. Such low pressures areachievable by 0.5 μm or less extensions of the z-piezo of a piezoscanner to which a tip array 10 is mounted, and pressures of about 0.01g/cm2 to about 0.1 g/cm2 can be applied by z-piezo extensions of lessthan 0.5 μm. This “buffering” pressure range allows one to manipulatethe tip array 10, substrate, or both to make initial contact betweentips 14 and substrate surface without compressing the tips 14, and thenusing the degree of compression of tips 14 (observed by changes inreflection of light off the inside surfaces of the tips 14) to achieve auniform degree of contact between tips 14 and substrate surface. Thisleveling ability is important, as non-uniform contact of the tips 14 ofthe tip array 10 can lead to non-uniform indicia. Given the large numberof tips 14 of the tip array 10 (e.g., 11 million in an example providedherein) and their small size, as a practical matter it may be difficultor impossible to know definitively if all of the tips 14 are in contactwith the surface. For example, a defect in a tip or the substratesurface, or an irregularity in a substrate surface, may result in asingle tip not making contact while all other tips 14 are in uniformcontact. Thus, the disclosed methods provide for at least substantiallyall of the tips 14 to be in contact with the substrate surface (e.g., tothe extent detectable). For example, at least 90%, at least 95%, atleast 96%, at least 97%, at least 98%, or at least 99% of the tips 14will be in contact with the substrate surface.

The leveling of the tip array 10 and substrate surface with respect toone another can be assisted by the transparent, or at least translucentnature of the tip array 10 and tip substrate layer 12, which allow fordetection of a change in reflection of light that is directed from thetop of the tip array 10 (i.e., behind the base of the tips 14 and commonsubstrate) through to the substrate surface. The intensity of lightreflected from the tips 14 of the tip array 10 increases upon contactwith the substrate surface (e.g., the internal surfaces of the tip array10 reflect light differently upon contact). By observing the change inreflection of light at each tip, the tip array 10 and/or the substratesurface can be adjusted to effect contact of substantially all or all ofthe tips 14 of the tip array 10 to the substrate surface. Thus, the tiparray 10 and common substrate preferably are translucent or transparentto allow for observing the change in light reflection of the tips 14upon contact with the substrate surface. Likewise, any rigid backingmaterial to which the tip array 10 is mounted is also preferably atleast transparent or translucent.

The contacting time for the tips 14 can be from about 0.001 seconds toabout 60 seconds. For example, the minimum contact time can be about0.001, 0.01, 0.1, 1, 10, 20, 30, 40, 50, or 60 seconds. For example, themaximum contact time can be about 0.001, 0.01, 0.1, 1, 10, 20, 30, 40,50, or 60 seconds. The contacting force can be controlled by alteringthe z-piezo of the piezo scanner or by other means that allow forcontrolled application of force across the tip array 10.

The substrate surface can be contacted with a tip array 10 a pluralityof times, wherein the tip array 10, the substrate surface or both moveto allow for different portions of the substrate surface to becontacted. The time and pressure of each contacting step can be the sameor different, depending upon the desired pattern. The shape of theindicia or patterns has no practical limitation, and can include dots,lines (e.g., straight or curved, formed from individual dots orcontinuously), a preselected pattern, or any combination thereof.

The indicia resulting from the disclosed methods have a high degree ofsameness, and thus are uniform or substantially uniform in size, andpreferably also in shape. The individual indicia feature size (e.g., adot or line width) is highly uniform, for example within a tolerance ofabout 5%, or about 1%, or about 0.5%. The tolerance can be about 0.9%,about 0.8%, about 0.7%, about 0.6%, about 0.4%, about 0.3%, about 0.2%,or about 0.1%. Non-uniformity of feature size and/or shape can lead toroughness of indicia that can be undesirable for sub-micron typepatterning.

The feature size can be about 10 nm to about 1 mm, about 10 nm to about500 μm, about 10 nm to about 100 μm, about 50 nm to about 100 μm, about50 nm to about 50 μm, about 50 nm to about 10 μm, about 50 nm to about 5μm, or about 50 nm to about 1 μm. Features sizes can be less than 1 μm,less than about 900 nm, less than about 800 nm, less than about 700 nm,less than about 600 nm, less than about 500 nm, less than about 400 nm,less than about 300 nm, less than about 200 nm, less than about 100 nm,or less than about 90 nm.

Patterning Compositions

For ink-based patterning, patterning compositions suitable for use inthe disclosed methods include both homogeneous and heterogeneouscompositions, the latter referring to a composition having more than onecomponent, for example combinations of any one or more of the componentsdescribed herein. The patterning composition is coated on the tip array.The term “coating,” as used herein when referring to the patterningcomposition, refers both to coating of the tip array as well adsorptionand absorption by the tip array of the patterning composition. Uponcoating of the tip array with the patterning composition, the patterningcomposition can be patterned on a substrate surface using the tip array.

Patterning compositions can be liquids, solids, semi-solids, and thelike. Patterning compositions suitable for use include, but are notlimited to, molecular solutions, polymer solutions, pastes, gels,creams, glues, resins, epoxies, adhesives, metal films, particulates,solders, etchants, and combinations thereof.

Patterning compositions can include materials such as, but not limitedto, monolayer-forming species, thin film-forming species, oils,colloids, metals, metal complexes, metal oxides, ceramics, organicspecies (e.g., moieties comprising a carbon-carbon bond, such as smallmolecules, polymers, polymer precursors, proteins, antibodies, and thelike), polymers (e.g., both non-biological polymers and biologicalpolymers such as single and double stranded DNA, RNA, and the like),polymer precursors, dendrimers, nanoparticles, and combinations thereof.In some embodiments, one or more components of a patterning compositionincludes a functional group suitable for associating with a substrate,for example, by forming a chemical bond, by an ionic interaction, by aVan der Waals interaction, by an electrostatic interaction, bymagnetism, by adhesion, and combinations thereof.

The composition can be formulated to control its viscosity, via routinemethods without undue experimentation. Parameters that can control inkviscosity include, but are not limited to, solvent composition, solventconcentration, thickener composition, thickener concentration, particlessize of a component, the molecular weight of a polymeric component, thedegree of cross-linking of a polymeric component, the free volume (i.e.,porosity) of a component, the swellability of a component, ionicinteractions between ink components (e.g., solvent-thickenerinteractions), and combinations thereof.

In some embodiments, the patterning composition comprises an additive,such as a solvent, a thickening agent, an ionic species (e.g., a cation,an anion, a zwitterion, etc.), a carrier matrix (e.g., polyethyleneglycol or agarose), the concentration of which can be selected to adjustone or more of the viscosity, the dielectric constant, the conductivity,the tonicity, the density, and the like.

Suitable thickening agents include, but are not limited to, metal saltsof carboxyalkylcellulose derivatives (e.g., sodiumcarboxymethylcellulose), alkylcellulose derivatives (e.g.,methylcellulose and ethylcellulose), partially oxidized alkylcellulosederivatives (e.g., hydroxyethylcellulose, hydroxypropylcellulose andhydroxypropylmethylcellulose), starches, polyacrylamide gels,homopolymers of poly-N-vinylpyrrolidone, poly(alkyl ethers) (e.g.,polyethylene oxide, polyethylene glycol, and polypropylene oxide), agar,agarose, xanthan gums, gelatin, dendrimers, colloidal silicon dioxide,lipids (e.g., fats, oils, steroids, waxes, glycerides of fatty acids,such as oleic, linoleic, linolenic, and arachidonic acid, and lipidbilayers such as from phosphocholine) and combinations thereof. In someembodiments, a thickener is present in a concentration of about 0.5% toabout 25%, about 1% to about 20%, or about 5% to about 15% by weight ofa patterning composition.

Suitable solvents for a patterning composition include, but are notlimited to, water, C1-C8 alcohols (e.g., methanol, ethanol, propanol andbutanol), C6-C12 straight chain, branched and cyclic hydrocarbons (e.g.,hexane and cyclohexane), C6-C14 aryl and aralkyl hydrocarbons (e.g.,benzene and toluene), C3-C10 alkyl ketones (e.g., acetone), C3-C10esters (e.g., ethyl acetate), C4-C10 alkyl ethers, and combinationsthereof. In some embodiments, a solvent is present in a concentration ofabout 1% to about 99%, about 5% to about 95%, about 10% to about 90%,about 15% to about 95%, about 25% to about 95%, about 50% to about 95%,or about 75% to about 95% by weight of a patterning composition.

Patterning compositions can comprise an etchant. As used herein, an“etchant” refers to a component that can react with a surface to removea portion of the surface. Thus, an etchant is used to form a subtractivefeature by reacting with a surface and forming at least one of avolatile and/or soluble material that can be removed from the substrate,or a residue, particulate, or fragment that can be removed from thesubstrate by, for example, a rinsing or cleaning method. In someembodiments, an etchant is present in a concentration of about 0.5% toabout 95%, about 1% to about 90%, about 2% to about 85%, about 0.5% toabout 10%, or about 1% to about 10% by weight of the patterningcomposition.

Etchants suitable for use in the methods disclosed herein include, butare not limited to, an acidic etchant, a basic etchant, a fluoride-basedetchant, and combinations thereof. Acidic etchants suitable for use withthe present invention include, but are not limited to, sulfuric acid,trifluoromethanesulfonic acid, fluorosulfonic acid, trifluoroaceticacid, hydrofluoric acid, hydrochloric acid, carborane acid, andcombinations thereof. Basic etchants suitable for use with the presentinvention include, but are not limited to, sodium hydroxide, potassiumhydroxide, ammonium hydroxide, tetraalkylammonium hydroxide ammonia,ethanolamine, ethylenediamine, and combinations thereof. Fluoride-basedetchants suitable for use with the present invention include, but arenot limited to, ammonium fluoride, lithium fluoride, sodium fluoride,potassium fluoride, rubidium fluoride, cesium fluoride, franciumfluoride, antimony fluoride, calcium fluoride, ammoniumtetrafluoroborate, potassium tetrafluoroborate, and combinationsthereof.

The patterning composition can include a reactive component. As usedherein, a “reactive component” refers to a compound or species that hasa chemical interaction with a substrate. In some embodiments, a reactivecomponent in the ink penetrates or diffuses into the substrate. In someembodiments, a reactive component transforms, binds, or promotes bindingto exposed functional groups on the surface of the substrate. Reactivecomponents can include, but are not limited to, ions, free radicals,metals, acids, bases, metal salts, organic reagents, and combinationsthereof. Reactive components further include, without limitation,monolayer-forming species such as thiols, hydroxides, amines, silanols,siloxanes, and the like, and other monolayer-forming species known to aperson or ordinary skill in the art. The reactive component can bepresent in a concentration of about 0.001% to about 100%, about 0.001%to about 50%, about 0.001% to about 25%, about 0.001% to about 10%,about 0.001% to about 5%, about 0.001% to about 2%, about 0.001% toabout 1%, about 0.001% to about 0.5%, about 0.001% to about 0.05%, about0.01% to about 10%, about 0.01% to about 5%, about 0.01% to about 2%,about 0.01% to about 1%, about 10% to about 100%, about 50% to about99%, about 70% to about 95%, about 80% to about 99%, about 0.001%, about0.005%, about 0.01%, about 0.1%, about 0.5%, about 1%, about 2%, orabout 5% weight of the patterning composition.

The patterning composition can comprise a conductive and/orsemi-conductive component. As used herein, a “conductive component”refers to a compound or species that can transfer or move electricalcharge. Conductive and semi-conductive components include, but are notlimited to, a metal, a nanoparticle, a polymer, a cream solder, a resin,and combinations thereof. In some embodiments, a conductive component ispresent in a concentration of about 1% to about 100%, about 1% to about10%, about 5% to about 100%, about 25% to about 100%, about 50% to about100%, about 75% to about 99%, about 2%, about 5%, about 90%, about 95%by weight of the patterning composition.

Metals suitable for use in a patterning composition include, but are notlimited to, a transition metal, aluminum, silicon, phosphorous, gallium,germanium, indium, tin, antimony, lead, bismuth, alloys thereof, andcombinations thereof.

The patterning composition can comprise a semi-conductive polymer.Semi-conductive polymers suitable for use with the present inventioninclude, but are not limited to, a polyaniline, apoly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), a polypyrrole,an arylene vinylene polymer, a polyphenylenevinylene, a polyacetylene, apolythiophene, a polyimidazole, and combinations thereof.

The patterning composition can include an insulating component. As usedherein, an “insulating component” refers to a compound or species thatis resistant to the movement or transfer of electrical charge. In someembodiments, an insulating component has a dielectric constant of about1.5 to about 8 about 1.7 to about 5, about 1.8 to about 4, about 1.9 toabout 3, about 2 to about 2.7, about 2.1 to about 2.5, about 8 to about90, about 15 to about 85, about 20 to about 80, about 25 to about 75, orabout 30 to about 70. Insulating components suitable for use in themethods disclosed herein include, but are not limited to, a polymer, ametal oxide, a metal carbide, a metal nitride, monomeric precursorsthereof, particles thereof, and combinations thereof. Suitable polymersinclude, but are not limited to, a polydimethylsiloxane, asilsesquioxane, a polyethylene, a polypropylene, a polyimide, andcombinations thereof. In some embodiments, for example, an insulatingcomponent is present in a concentration of about 1% to about 95%, about1% to about 80%, about 1% to about 50%, about 1% to about 20%, about 1%to about 10%, about 20% to about 95%, about 20% to about 90%, about 40%to about 80%, about 1%, about 5%, about 10%, about 90%, or about 95% byweight of the patterning composition.

The patterning composition can include a masking component. As usedherein, a “masking component” refers to a compound or species that uponreacting forms a surface feature resistant to a species capable ofreacting with the surrounding surface. Masking components suitable foruse with the present invention include materials commonly employed intraditional photolithography methods as “resists” (e.g., photoresists,chemical resists, self-assembled monolayers, etc.). Masking componentssuitable for use in the disclosed methods include, but are not limitedto, a polymer such as a polyvinylpyrollidone,poly(epichlorohydrin-co-ethyleneoxide), a polystyrene, apoly(styrene-co-butadiene), a poly(4-vinylpyridine-co-styrene), an amineterminated poly(styrene-co-butadiene), apoly(acrylonitrile-co-butadiene), a styrene-butadiene-styrene blockcopolymer, a styrene-ethylene-butylene block linear copolymer, apolystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene, apoly(styrene-co-maleic anhydride), apolystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene-graft-maleicanhydride, a polystyrene-block-polyisoprene-block-polystyrene, apolystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene, apolynorbornene, a dicarboxy terminatedpoly(acrylonitrile-co-butadiene-co-acrylic acid), a dicarboxy terminatedpoly(acrylonitrile-co-butadiene), a polyethyleneimine, a poly(carbonateurethane), a poly(acrylonitrile-co-butadiene-co-styrene), apoly(vinylchloride), a poly(acrylic acid), a poly(methylmethacrylate), apoly(methyl methacrylate-co-methacrylic acid), a polyisoprene, apoly(1,4-butylene terephthalate), a polypropylene, a poly(vinylalcohol), a poly(1,4-phenylene sulfide), a polylimonene, apoly(vinylalcohol-co-ethylene), apoly[N,N′-(1,3-phenylene)isophthalamide], a poly(1,4-phenyleneether-ether-sulfone), a poly(ethyleneoxide), a poly[butyleneterephthalate-co-poly(alkylene glycol) terephthalate], a poly(ethyleneglycol) diacrylate, a poly(4-vinylpyridine), a poly(DL-lactide), apoly(3,3′,4,4′-benzophenonetetracarboxylicdianhydride-co-4,4′-oxydianiline/1,3-phenylenediamine), an agarose, apolyvinylidene fluoride homopolymer, a styrene butadiene copolymer, aphenolic resin, a ketone resin, a4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxane, a salt thereof, andcombinations thereof. In some embodiments, a masking component ispresent in a concentration of about 1% to about 10%, about 1% to about5%, or about 2% by weight of the patterning composition.

The patterning composition can include a conductive component and areactive component. For example, a reactive component can promote atleast one of: penetration of a conductive component into a surface,reaction between the conductive component and a surface, adhesionbetween a conductive feature and a surface, promoting electrical contactbetween a conductive feature and a surface, and combinations thereof.Surface features formed by reacting this patterning composition includeconductive features selected from the group consisting of: additivenon-penetrating, additive penetrating, subtractive penetrating, andconformal penetrating surface features.

The patterning composition can comprise an etchant and a conductivecomponent, for example, suitable for producing a subtractive surfacefeature having a conductive feature inset therein.

The patterning composition can comprise an insulating component and areactive component. For example, a reactive component can promote atleast one of: penetration of an insulating component into a surface,reaction between the insulating component and a surface, adhesionbetween an insulating feature and a surface, promoting electricalcontact between an insulating feature and a surface, and combinationsthereof. Surface features formed by reacting this patterning compositioninclude insulating features selected from the group consisting of:additive non-penetrating, additive penetrating, subtractive penetrating,and conformal penetrating surface features.

The patterning composition can comprise an etchant and an insulatingcomponent, for example, suitable for producing a subtractive surfacefeature having an insulating feature inset therein.

The patterning composition can comprise a conductive component and amasking component, for example, suitable for producing electricallyconductive masking features on a surface.

Other contemplated components of a patterning composition suitable foruse with the disclosed methods include thiols, 1,9-nonanedithiolsolution, silane, silazanes, alkynes cystamine, N-Fmoc protected aminothiols, biomolecules, DNA, proteins, antibodies, collagen, peptides,biotin, and carbon nanotubes.

For a description of patterning compounds and patterning compositions,and their preparation and use, see Xia and Whitesides, Angew. Chem. Int.Ed., 37, 550-575 (1998) and references cited therein; Bishop et al.,Curr. Opinion Colloid & Interface Sci., 1, 127-136 (1996); Calvert, J.Vac. Sci. Technol. B, 11, 2155-2163 (1993); Ulman, Chem. Rev., 96:1533(1996) (alkanethiols on gold); Dubois et al., Annu. Rev. Phys. Chem.,43:437 (1992) (alkanethiols on gold); Ulman, An Introduction toUltrathin Organic Films: From Langmuir-Blodgett to Self-Assembly(Academic, Boston, 1991) (alkanethiols on gold); Whitesides, Proceedingsof the Robert A. Welch Foundation 39th Conference On Chemical ResearchNanophase Chemistry, Houston, Tex., pages 109-121 (1995) (alkanethiolsattached to gold); Mucic et al. Chem. Commun. 555-557 (1996) (describesa method of attaching 3′ thiol DNA to gold surfaces); U.S. Pat. No.5,472,881 (binding of oligonucleotide-phosphorothiolates to goldsurfaces); Burwell, Chemical Technology, 4, 370-377 (1974) and Matteucciand Caruthers, J. Am. Chem. Soc., 103, 3185-3191 (1981) (binding ofoligonucleotides-alkylsiloxanes to silica and glass surfaces); Grabar etal., Anal. Chem., 67, 735-743 (binding of aminoalkylsiloxanes and forsimilar binding of mercaptoalkylsiloxanes); Nuzzo et al., J. Am. Chem.Soc., 109, 2358 (1987) (disulfides on gold); Allara and Nuzzo, Langmuir,1, 45 (1985) (carboxylic acids on aluminum); Allara and Tompkins, J.Colloid Interfate Sci., 49, 410-421 (1974) (carboxylic acids on copper);Iler, The Chemistry Of Silica, Chapter 6, (Wiley 1979) (carboxylic acidson silica); Timmons and Zisman, J. Phys. Chem., 69, 984-990 (1965)(carboxylic acids on platinum); Soriaga and Hubbard, J. Am. Chem. Soc.,104, 3937 (1982) (aromatic ring compounds on platinum); Hubbard, Acc.Chem. Res., 13, 177 (1980) (sulfolanes, sulfoxides and otherfunctionalized solvents on platinum); Hickman et al., J. Am. Chem. Soc.,111, 7271 (1989) (isonitriles on platinum); Maoz and Sagiv, Langmuir, 3,1045 (1987) (silanes on silica); Maoz and Sagiv, Langmuir, 3, 1034(1987) (silanes on silica); Wasserman et al., Langmuir, 5, 1074 (1989)(silanes on silica); Eltekova and Eltekov, Langmuir, 3,951 (1987)(aromatic carboxylic acids, aldehydes, alcohols and methoxy groups ontitanium dioxide and silica); and Lec et al., J. Phys. Chem., 92, 2597(1988) (rigid phosphates on metals); Lo et al., J. Am. Chem. Soc., 118,11295-11296 (1996) (attachment of pyrroles to superconductors); Chen etal., J. Am. Chem. Soc., 117, 6374-5 (1995) (attachment of amines andthiols to superconductors); Chen et al., Langmuir, 12, 2622-2624 (1996)(attachment of thiols to superconductors); McDevitt et al., U.S. Pat.No. 5,846,909 (attachment of amines and thiols to superconductors); Xuet al., Langmuir, 14, 6505-6511 (1998) (attachment of amines tosuperconductors); Mirkin et al., Adv. Mater. (Weinheim, Ger.), 9,167-173 (1997) (attachment of amines to superconductors); Hovis et al.,J. Phys. Chem. B, 102, 6873-6879 (1998) (attachment of olefins anddienes to silicon); Hovis et al., Surf. Sci., 402-404, 1-7 (1998)(attachment of olefins and dienes to silicon); Hovis et al., J. Phys.Chem. B, 101, 9581-9585 (1997) (attachment of olefins and dienes tosilicon); Hamers et al., J. Phys. Chem. B, 101, 1489-1492 (1997)(attachment of olefins and dienes to silicon); Hamers et al., U.S. Pat.No. 5,908,692 (attachment of olefins and dienes to silicon); Ellison etal., J. Phys. Chem. B, 103, 6243-6251 (1999) (attachment ofisothiocyanates to silicon); Ellison et al., J. Phys. Chem. B, 102,8510-8518 (1998) (attachment of azoalkanes to silicon); Ohno et al.,Mol. Cryst. Liq. Cryst. Sci. Technol., Sect. A, 295, 487-490 (1997)(attachment of thiols to GaAs); Reuter et al., Mater. Res. Soc. Symp.Proc., 380, 119-24 (1995) (attachment of thiols to GaAs); Bain, Adv.Mater. (Weinheim, Fed. Repub. Ger.), 4, 591-4 (1992) (attachment ofthiols to GaAs); Sheen et al., J. Am. Chem. Soc., 114, 1514-15 (1992)(attachment of thiols to GaAs); Nakagawa et al., Jpn. J. Appl. Phys.,Part 1, 30, 3759-62 (1991) (attachment of thiols to GaAs); Lunt et al.,J. Appl. Phys., 70, 7449-67 (1991) (attachment of thiols to GaAs); Luntet al., J. Vac. Sci. Technol., B, 9, 2333-6 (1991) (attachment of thiolsto GaAs); Yamamoto et al., Langmuir ACS ASAP, web release numberIa990467r (attachment of thiols to InP); Gu et al., J. Phys. Chem. B,102, 9015-9028 (1998) (attachment of thiols to InP); Menzel et al., Adv.Mater. (Weinheim, Ger.), 11, 131-134 (1999) (attachment of disulfides togold); Yonezawa et al., Chem. Mater., 11, 33-35 (1999) (attachment ofdisulfides to gold); Porter et al., Langmuir, 14, 7378-7386 (1998)(attachment of disulfides to gold); Son et al., J. Phys. Chem., 98,8488-93 (1994) (attachment of nitriles to gold and silver); Steiner etal., Langmuir, 8, 2771-7 (1992) (attachment of nitriles to gold andcopper); Solomun et al., J. Phys. Chem., 95, 10041-9 (1991) (attachmentof nitriles to gold); Solomun et al., Ber. Bunsen-Ges. Phys. Chem., 95,95-8 (1991) (attachment of nitriles to gold); Henderson et al., Inorg.Chim. Acta, 242, 115-24 (1996) (attachment of isonitriles to gold); Hucet al., J. Phys. Chem. B, 103, 10489-10495 (1999) (attachment ofisonitriles to gold); Hickman et al., Langmuir, 8, 357-9 (1992)(attachment of isonitriles to platinum); Steiner et al., Langmuir, 8,90-4 (1992) (attachment of amines and phospines to gold and attachmentof amines to copper); Mayya et al., J. Phys. Chem. B, 101, 9790-9793(1997) (attachment of amines to gold and silver); Chen et al., Langmuir,15, 1075-1082 (1999) (attachment of carboxylates to gold); Tao, J. Am.Chem. Soc., 115, 4350-4358 (1993) (attachment of carboxylates to copperand silver); Laibinis et al., J. Am. Chem. Soc., 114, 1990-5 (1992)(attachment of thiols to silver and copper); Laibinis et al., Langmuir,7, 3167-73 (1991) (attachment of thiols to silver); Fenter et al.,Langmuir, 7, 2013-16 (1991) (attachment of thiols to silver); Chang etal., Am. Chem. Soc., 116, 6792-805 (1994) (attachment of thiols tosilver); Li et al., J. Phys. Chem., 98, 11751-5 (1994) (attachment ofthiols to silver); Li et al., Report, 24 pp (1994) (attachment of thiolsto silver); Tarlov et al., U.S. Pat. No. 5,942,397 (attachment of thiolsto silver and copper); Waldeck, et al., PCT application WO/99/48682(attachment of thiols to silver and copper); Gui et al., Langmuir, 7,955-63 (1991) (attachment of thiols to silver); Walczak et al., J. Am.Chem. Soc., 113, 2370-8 (1991) (attachment of thiols to silver);Sangiorgi et al., Gazz. Chim. Ital., 111, 99-102 (1981) (attachment ofamines to copper); Magallon et al., Book of Abstracts, 215th ACSNational Meeting, Dallas, Mar. 29-Apr. 2, 1998, COLL-048 (attachment ofamines to copper); Patil et al., Langmuir, 14, 2707-2711 (1998)(attachment of amines to silver); Sastry et al., J. Phys. Chem. B, 101,4954-4958 (1997) (attachment of amines to silver); Bansal et al., J.Phys. Chem. B. 102, 4058-4060 (1998) (attachment of alkyl lithium tosilicon); Bansal et al., J. Phys. Chem. B, 102, 1067-1070 (1998)(attachment of alkyl lithium to silicon); Chidsey, Book of Abstracts,214th ACS National Meeting, Las Vegas, Nev., Sep. 7-11, 1997, I&EC-027(attachment of alkyl lithium to silicon); Song, J. H., Thesis,University of California at San Diego (1998) (attachment of alkyllithium to silicon dioxide); Meyer et al., J. Am. Chem. Soc., 110,4914-18 (1988) (attachment of amines to semiconductors); Brazdil et al.J. Phys. Chem., 85, 1005-14 (1981) (attachment of amines tosemiconductors); James et al., Langmuir, 14, 741-744 (1998) (attachmentof proteins and peptides to glass); Bernard et al., Langmuir, 14,2225-2229 (1998) (attachment of proteins to glass, polystyrene, gold,silver and silicon wafers); Pereira et al., J. Mater. Chem., 10, 259(2000) (attachment of silazanes to SiO2); Pereira et al., J. Mater.Chem., 10, 259 (2000) (attachment of silazanes to SiO2); Dammel,Diazonaphthoquinone Based Resists (1st ed., SPIE Optical EngineeringPress, Bellingham, Wash., 1993) (attachment of silazanes to SiO2);Anwander et al., J. Phys. Chem. B, 104, 3532 (2000) (attachment ofsilazanes to SiO2); Slavov et al., J. Phys. Chem., 104, 983 (2000)(attachment of silazanes to SiO2).

For a description of patterning compounds and patterning compositions,and their preparation and use, see Xia and Whitesides, Angew. Chem. Int.Ed., 37, 550-575 (1998) and references cited therein; Bishop et al.,Curr. Opinion Colloid & Interface Sci., 1, 127-136 (1996); Calvert, J.Vac. Sci. Technol. B, 11, 2155-2163 (1993); Ulman, Chem. Rev., 96:1533(1996) (alkanethiols on gold); Dubois et al., Annu. Rev. Phys. Chem.,43:437 (1992) (alkanethiols on gold); Ulman, An Introduction toUltrathin Organic Films: From Langmuir-Blodgett to Self-Assembly(Academic, Boston, 1991) (alkanethiols on gold); Whitesides, Proceedingsof the Robert A. Welch Foundation 39th Conference On Chemical ResearchNanophase Chemistry, Houston, Tex., pages 109-121 (1995) (alkanethiolsattached to gold); Mucic et al. Chem. Commun. 555-557 (1996) (describesa method of attaching 3′ thiol DNA to gold surfaces); U.S. Pat. No.5,472,881 (binding of oligonucleotide-phosphorothiolates to goldsurfaces); Burwell, Chemical Technology, 4, 370-377 (1974) and Matteucciand Caruthers, J. Am. Chem. Soc., 103, 3185-3191 (1981) (binding ofoligonucleotides-alkylsiloxanes to silica and glass surfaces); Grabar etal., Anal. Chem., 67, 735-743 (binding of aminoalkylsiloxanes and forsimilar binding of mercaptoalkylsiloxanes); Nuzzo et al., J. Am. Chem.Soc., 109, 2358 (1987) (disulfides on gold); Allara and Nuzzo, Langmuir,1, 45 (1985) (carboxylic acids on aluminum); Allara and Tompkins, J.Colloid Interfate Sci., 49, 410-421 (1974) (carboxylic acids on copper);Iler, The Chemistry Of Silica, Chapter 6, (Wiley 1979) (carboxylic acidson silica); Timmons and Zisman, J. Phys. Chem., 69, 984-990 (1965)(carboxylic acids on platinum); Soriaga and Hubbard, J. Am. Chem. Soc.,104, 3937 (1982) (aromatic ring compounds on platinum); Hubbard, Acc.Chem. Res., 13, 177 (1980) (sulfolanes, sulfoxides and otherfunctionalized solvents on platinum); Hickman et al., J. Am. Chem. Soc.,111, 7271 (1989) (isonitriles on platinum); Maoz and Sagiv, Langmuir, 3,1045 (1987) (silanes on silica); Maoz and Sagiv, Langmuir, 3, 1034(1987) (silanes on silica); Wasserman et al., Langmuir, 5, 1074 (1989)(silanes on silica); Eltekova and Eltekov, Langmuir, 3,951 (1987)(aromatic carboxylic acids, aldehydes, alcohols and methoxy groups ontitanium dioxide and silica); and Lec et al., J. Phys. Chem., 92, 2597(1988) (rigid phosphates on metals); Lo et al., J. Am. Chem. Soc., 118,11295-11296 (1996) (attachment of pyrroles to superconductors); Chen etal., J. Am. Chem. Soc., 117, 6374-5 (1995) (attachment of amines andthiols to superconductors); Chen et al., Langmuir, 12, 2622-2624 (1996)(attachment of thiols to superconductors); McDevitt et al., U.S. Pat.No. 5,846,909 (attachment of amines and thiols to superconductors); Xuet al., Langmuir, 14, 6505-6511 (1998) (attachment of amines tosuperconductors); Mirkin et al., Adv. Mater. (Weinheim, Ger.), 9,167-173 (1997) (attachment of amines to superconductors); Hovis et al.,J. Phys. Chem. B, 102, 6873-6879 (1998) (attachment of olefins anddienes to silicon); Hovis et al., Surf. Sci., 402-404, 1-7 (1998)(attachment of olefins and dienes to silicon); Hovis et al., J. Phys.Chem. B, 101, 9581-9585 (1997) (attachment of olefins and dienes tosilicon); Hamers et al., J. Phys. Chem. B, 101, 1489-1492 (1997)(attachment of olefins and dienes to silicon); Hamers et al., U.S. Pat.No. 5,908,692 (attachment of olefins and dienes to silicon); Ellison etal., J. Phys. Chem. 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Substrates to be Patterned

Any suitable substrates can be patterned, depending on the patterningmethods used. For example, for beam pen lithography any photosensitivesubstrate or substrate layer can be patterned. For electrochemicaldeposition and suitable electro-sensitive substrate or substrate layercan be used. For thermal deposition, a thermal sensitive substrate canbe used or a thermal sensitive ink composition can be deposited on anysubstrate.

Substrates can include, but are not limited to, metals, alloys,composites, crystalline materials, amorphous materials, conductors,semiconductors, optics, fibers, inorganic materials, glasses, ceramics(e.g., metal oxides, metal nitrides, metal silicides, and combinationsthereof), zeolites, polymers, plastics, organic materials, minerals,biomaterials, living tissue, bone, films thereof, thin films thereof,laminates thereof, foils thereof, composites thereof, and combinationsthereof. A substrate can comprise a semiconductor such as, but notlimited to: crystalline silicon, polycrystalline silicon, amorphoussilicon, p-doped silicon, n-doped silicon, silicon oxide, silicongermanium, germanium, gallium arsenide, gallium arsenide phosphide,indium tin oxide, and combinations thereof. A substrate can comprise aglass such as, but not limited to, undoped silica glass (SiO2),fluorinated silica glass, borosilicate glass, borophosphorosilicateglass, organosilicate glass, porous organosilicate glass, andcombinations thereof. The substrate can be a non-planar substrate, suchas pyrolytic carbon, reinforced carbon-carbon composite, a carbonphenolic resin, and the like, and combinations thereof. A substrate cancomprise a ceramic such as, but not limited to, silicon carbide,hydrogenated silicon carbide, silicon nitride, silicon carbonitride,silicon oxynitride, silicon oxycarbide, high-temperature reusablesurface insulation, fibrous refractory composite insulation tiles,toughened unipiece fibrous insulation, low-temperature reusable surfaceinsulation, advanced reusable surface insulation, and combinationsthereof. A substrate can comprise a flexible material, such as, but notlimited to: a plastic, a metal, a composite thereof, a laminate thereof,a thin film thereof, a foil thereof, and combinations thereof.

The substrate can comprise a compressible material. The compressiblematerial can be layered on top of a substrate as described herein.Examples of compressible materials include, but are not limited to,polymers, metals (e.g., soft metals), foils, films, or the like.Non-limiting examples of a compressible layer includepolymethylmethacrylate (PMMA), polydimethylsiloxane (PDMS),nitrocellulose, and combinations thereof.

The substrate can comprise a material that can be desorbed uponapplication of electrical energy. Non-limiting examples of such amaterial include 16-mercaptohexadecanoic acid (MHA) and octadecanethiol(ODT), alkane thiols, and phosphonic acids.

Surfaces to be Patterned by pBPL

The surfaces to pattern by BPL can include any suitable substrate, suchas those described above which is photosensitive or includes aphotosensitive layer. For example, the photosensitive substrate orphotosensitive layer 20 can be a resist layer. The resist layer can beany known resist material, for example SHIPLEY1805 (MicroChem Inc.).Other suitable resist materials include, but are not limited to,Shipley1813 (MicroChem Inc.), Shipley1830 (MicroChem Inc.), PHOTORESISTAZ1518 (MicroChemicals, Germany), PHOTORESIST AZ5214 (MicroChemicals,Germany), SU-8, and combinations thereof. Other examples ofphotosensitive materials include, but are not limited to, liquidcrystals and metals. For examples, the substrate can include metal saltsthat can be reduced when exposed to the radiation. Substrates suitablefor use in methods disclosed herein include, but are not limited to,metals, alloys, composites, crystalline materials, amorphous materials,conductors, semiconductors, optics, fibers, inorganic materials,glasses, ceramics (e.g., metal oxides, metal nitrides, metal silicides,and combinations thereof), zeolites, polymers, plastics, organicmaterials, minerals, biomaterials, living tissue, bone, and laminatesand combinations thereof. The substrate can be in the form of films,thin films, foils, and combinations thereof. A substrate can comprise asemiconductor including, but not limited to one or more of: crystallinesilicon, polycrystalline silicon, amorphous silicon, p-doped silicon,n-doped silicon, silicon oxide, silicon germanium, germanium, galliumarsenide, gallium arsenide phosphide, indium tin oxide, graphene, andcombinations thereof. A substrate can comprise a glass including, butnot limited to, one or more of undoped silica glass (SiO2), fluorinatedsilica glass, borosilicate glass, borophosphorosilicate glass,organosilicate glass, porous organosilicate glass, and combinationsthereof. The substrate can be a non-planar substrate, including, but notlimited to, one or more of pyrolytic carbon, reinforced carbon-carboncomposite, a carbon phenolic resin, and combinations thereof. Asubstrate can comprise a ceramic including, but not limited to, one ormore of silicon carbide, hydrogenated silicon carbide, silicon nitride,silicon carbonitride, silicon oxynitride, silicon oxycarbide,high-temperature reusable surface insulation, fibrous refractorycomposite insulation tiles, toughened unipiece fibrous insulation,low-temperature reusable surface insulation, advanced reusable surfaceinsulation, and combinations thereof. A substrate can comprise aflexible material, including, but not limited to one or more of: aplastic, a metal, a composite thereof, a laminate thereof, a thin filmthereof, a foil thereof, and combinations thereof.

The photosensitive substrate or the photosensitive layer 20 can have anysuitable thickness, for example in a range of about 100 nm to about 5000nm. For example, the minimum photosensitive substrate or photosensitivelayer 20 thickness can be about 100, 150, 200, 250, 300, 350, 400, 450or 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1500, 2000,2500, 3000, 3500, 4000, 4500, or 5000 nm. For example, the maximumphotosensitive substrate or photosensitive layer 20 thickness can beabout 100, 150, 200, 250, 300, 350, 400, 450 or 500, 550, 600, 650, 700,750, 800, 850, 900, 950, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500,or 5000 nm. The diameter of the indicia formed by the tip array 10 canbe modulated by modifying the resist material used and/or the thicknessof the photosensitive substrate or photosensitive layer 20. For example,under the same radiation conditions, a thicker photosensitive layer canresult in indicia having larger diameters. At constant photosensitivelayer thickness, an increase in radiation intensity can result inindicia having larger diameters.

In one embodiment a substrate is spin-coated with a layer ofpositive-tone photoresist (for example, SHIPLEY1805). The photoresistcan be applied by pre-diluting with propylene glycol mononmethyl etheracetate at a ratio selected based on the desired thickness of the resistlayer. For example, if a 40 nm thick photoresist layer is desired, thephotoresist can be diluted with the acetate in a ratio of 1:4. If a 150nm thick photoresist layer is desired the dilution ratio can be, forexample, 1:1. The photoresist coated substrate can be soft-baked, forexample, on a hot plate at 115° C. for about one minute. To improve theperformance of the resist for lift-off processing, a layer of lift-offresist can optionally be applied. For example LOR 3A lift-off resist(available from MicroChem Corp) can be used. The lift-off resist can bespin coated onto the photoresist for example at 4000 rpm for one minuteand can then be baked, for example at 180° C. for about five minutes.

EXAMPLES Examples 1 Formation of BPL Tip Array

BPL tip arrays were fabricated starting from a PPL tip array inaccordance with known methods. See Huo et al., Science 2008, 321,1658-60. Hard PDMS composed of 3.4 g of vinyl-compound-rich prepolymer(VDT-731, Gelest) and 1.0 g of hydrosilane-rich crosslinker (HMS-301)was poured onto a Si master and followed by curing at 80° C. for 24hours. After peeling the PPL tip array off the Si master, it was exposedto air plasma at 200 mb and 60 W for 1 min. Next, a 5 nm layer of Tifollowed by a 100 nm layer of Au was evaporated on the tip array at 0.25Å/s to make the entire tip array opaque. In order to open apertures inthe apex of the pyramidal tips PMMA (950c 7, MicroChem Inc., USA) wasspin-coated onto the metal-coated tip array at 1000 rpm for 1 min andbaked at 150° C. for 5 minutes. The PMMA coating was repeated anadditional 1 to 3 times to ensure complete coverage. Reactive ionetching was then employed to homogeneously etch the PMMA until theapexes of the tips were exposed. The array was observed in an opticalmicroscope every minute in order to stop the etch precisely when onlythe apexes were exposed. Typically, etching with 25 W for 5 minutes in100 mTorr O₂ was sufficient. The gold at the apex of each pen wasremoved through soaking in a selective chemical etch, using theremaining portion of the PMMA as an etch mask. The chemical etch wasperformed for about 50 seconds, leaving an aperture at the tip of eachtip in the array. Finally, rinsing in acetone was used to remove theremaining PMMA. FIG. 26B provides a schematic illustration of theaperture formation process. Apertures having a diameter of about 100 nmwere formed in the apexes of the tips.

Example 2 Patterning with pBPL without Tip Array Movement

A BPL tip array was mounted on a scanning probe lithography platform andleveled with respect to a photoresist-coated Si wafer utilizing anoptical leveling procedure. To expose a region of the resist, the tipswere brought into contact with the resist surface and UV light with awavelength λ of about 405 nm was shined on the back side of the tiparray and held for a specific exposure time. While sub-λ sized aperturesof the tip arrays blocked the propagating light, evanescent lightextended into the photoresist with an intensity that decayedexponentially with depth into the resist surface.

To optimize the exposure time, a dose-test was performed in which thetip array wrote a series of dots (FIG. 27A) with exposure times between2 and 4 seconds. In this experiment, the exposure times were modulatedby controlling the mirrors to print in “grayscale,” which modulated theduty cycle of each mirror. This provided a simple way to adjust theexposure dose received by each pixel patterned. At an exposure dose of 2seconds, the patterned features had a diameter of 122±12 nn, which issubstantially smaller than λ/2. At longer exposure times, largerfeatures were patterned (FIG. 27A).

In contrast to pattern dots with the tips held still, moving the tipslinearly across the sample while in contact with the sample allows oneto pattern lines. Gold lines with widths of about 375 nm, about 750 nm,about 1.125 μm, and about 1.5 μm were patterned by scanning the tiparray at 4, 2, 1, and 0.5 μm/s, respectively. The structures written bythe tips were visualized by scanning electron microscopy after beingcoated with 5 nm of Cr and 25 nm of Au and subjected to solvent lift offto remove the remaining photoresist.

Example 3 Patterning by pBPL with Raster Scanning of the Tip Array

To generate a large scale image, the tip array was raster scanned acrossa sample while a DMD displayed images extracted from a master image. Toachieve registry between the projected image and the tips, an alignmentprocedure as described above was used.

Once good alignment was achieved, the large scale pattern was writtenwhile the actions of the DMD and the scanning probe system werecontrolled by the software program as described above.

Referring to FIG. 28, a tip array having 10,000 tips addressing 10,000points each creating a cm² image. The features had a diameter of about300 nm. This demonstrates the high quality control of light frommacroscale to nanoscale achievable with embodiments of the disclosure.This ability corresponds to a four order magnitude increase in datatransfer rate as compared to conventional BPL. Fabrication of thispattern would not be possible using conventional optical techniques, andinstead would include the significantly more costly and complicatedelectron beam lithography (EBL) process.

Example 4 Generation of Circuit Patterns using pBPL

The utility of pBPL was evaluated by patterning functional circuits.Arrays of serpentine resistors with varying lengths were patterned. FIG.29A illustrates representative SEM images of the resistors. Allresistors required the coordination of multiple tips with the smallestlines requiring three tips and the largest lines requesting fifteentips. The largest lines were continuous wires having a length of 4 mmand a width of 2 μm. Current-voltage characterization of sixty-onedevices revealed that all measured devices had Ohmic character withresistances that depended linearly on the line length (FIG. 29B).

The sheet resistance of the resistance of resistors can be computed bycombining the slope of the linear fit in FIG. 29C to find r=0.32Ω/square, in agreement with the expected value of about 0.4 Ω/square fora 50 nm thick gold film.

In addition to resistors, planar capacitors, inductors, and surfaceacoustic wave sensors (SAWS) were also patterned, demonstrating a fullpallet of passive circuit elements that can be patterned usingembodiments of the disclosure (FIG. 29B). The capacitor illustrated inFIG. 29C was patterned using fifty-seven tips, the inductor waspatterned using fifty-one tips, and the SAWS was patterned using 101tips.

FIG. 30A illustrates electrical wire connections generated using pBPL.To evaluate the potential of pBPL to generate patterns in registry withexisting structures, semiconductor nanowires were dispersed on asubstrate and electrically connected by leads generated by pBPL (FIG.30B). An array consisting of 729 tips (27×27) and alignment markers wasused to pattern connections to sixty wires that had been located byoptical microscopy. Patterning of this type, which is traditionally doneby EBL, demonstrates the ability of pBPL to rapidly pattern in amask-free fashion with registry to an existing pattern. Once thepatterns were written, 59/60 of the wires were successfully connectedand after the lift-off of the photoresist, 40/60 working devices wereobtained. The electrical transport of the nanowire structuredemonstrated clear semiconducting behavior.

Example 5 Method of Making a Heat Actuation Tip Array

FIG. 11 provides a schematic illustration of a method of making a heatactuation tip array, the tip array being a silicon pen tip array.Heaters were fabricated by etching an indium tin oxide (ITO) coatedglass slide. ITO was chosen as an electrode material because it istransparent and a conductor. 25×25 mm² glass slides coated in 8 to 12Ω/sq ITO were purchased from Sigma Aldrich and cleaned chemically byrinsing in acetone, DI water, and isopropanol. They were then driedunder nitrogen. The slides were spin coated with a positive tonephotoresist (S1805-Shipley) at 4000 rpm for 40 s and baked on a hotplate for 1 minute at 115° C. Samples were then aligned in a maskaligner and exposed for 2 s and post-exposure baked for 1 minute at 115°C. Patterns were then developed in MF-24A (Shipley) for 60 s then rinsedin DI water and dried under nitrogen. In order to make the patternedphotoresist a better mask for etching, samples were hard baked for 4hours at 80° C.

To etch the ITO, a reactive ion etch was utilized. Samples were mountedon 4 inch (10 cm) wafers with photoresist and loaded into a deepreactive ion etch (DRIE-STS LpX Pegasus). The samples were etched under200 sccm of Argon that was held at 5 mTorr using 2500 W RF power and 40W delivered to the platen. Under these conditions, the etch rate of ITOwas found to be approximately 1 Å/s. The completion of the etch wasverified by using a multimeter to measure the background resistance andresistance of the devices. To remove the residual resist, samples weresoaked overnight in Remover PG (Microchem) on an 80° C. hot plate.Samples were visualized in a scanning electron microscope (FIG. 10C) toreveal the ITO coils and bus lines. In this figure, a 4×4 array of coilheaters is present.

Next, the slides were coated with PDMS placed on a Si wafer. Si wafers(NOVA Electronic Materials; resistivity 1-10 Ω·cm, (100) orientation,50±5 μm thick) with a 10,000 Å (±5%) SiO₂ layer on each side were usedfor fabricating the tip arrays. The wafers were cleaned in acetone,ethanol, then rinsed with water before use. In preparing the elastomerbase, PDMS and a curing agent (Sylgard 184 Silicone) were mixed in a10:1 ratio (w/w), and then degassed under vacuum (10-3 Ton) for 30 min.Uncured PDMS was spin-coated at 1,000 rpm for 30 s with a ramping speedof 1,000 rpm/s, followed by curing at 75° C. for 10 min. The averagethickness was determined by profilometry (Veeco, Dektak 150) to be88.5±1.3 μm. To increase the adhesion between the cured PDMS and Siwafers, epoxy (DAP Dow Corning, Silicone Rubber Aquarium Sealant) wasused by spin-coating it onto the cured PDMS. The epoxy was diluted withheptane (0.2 g epoxy and 2 mL heptane) to decrease the viscosity of theepoxy and, as a result, homogeneous film thickness less than 1 μm wereobtained. Oxygen-plasma-treated (60 W at a pressure of 100 mTorr) waferswere then placed on spin-coated epoxy/PDMS on clean glass slides,followed by curing at 75° C. for 1 h.

Photolithography was used to define square masks for the tip etchingprocedure. These squares were be between 120 μm and 140 μm (depending onthe thickness of the silicon wafer) and the edges of the squares must bealigned along the Si layers <110> direction. First, samples were treatedin oxygen plasma for 1 min at ˜100 mTorr at 30 W. This step can enhanceadhesion of the resist. Samples were then spin-coated with photoresist(S1805—Shipley) at 4000 rpm for 40 s and baked on a hot plate for 1minute at 115° C. Samples were then aligned using a mask aligner. Incontrast to previous HSL work, where the tip masks are aligned to beparallel to the edge of the silicon wafer, here the tip masks werealigned to predefined alignment markers on the ITO surface below. Thisalignment ensured that each tip rested above a heater. Samples wereexposed for 2 s and post-exposure baked for 1 minute at 115° C. Patternswere developed in MF-24A for 60 s then rinsed in DI water and driedunder nitrogen.

An anisotropic wet etch was used to define the tips. The edge of the Siwafer chip was passivated with PDMS to prevent etching in from thesides. Exposed SiO₂ was then selectively etched in isotropic bufferedhydrofluoric acid (Transene, 9% HF, BUFFER-HF Improved) for 9 min in apolystyrene petri dish and washed with water. To remove the photoresist,the wafer was cleaned in acetone, ethanol, and subsequently dried withflowing nitrogen. The wafer was then cleaned with oxygen plasma (1 minat 30 W at a pressure of 100 mTorr). O₂ plasma cleaning prior to Sietching was found to improve the uniformity of the tips. Samples wereimmediately transferred into 40 wt % KOH (333 g KOH in 500 mL DI water)(KOH from Sigma-Aldrich; 99.99% metal basis, semiconductor grade,product no. 306568) at 75° C. and held in the center of the etchant in aTeflon holder. The solution was continuously stirred to reduce theeffect of micro-masking by hydrogen bubbles generated by the reaction atthe Si surface. After 60-65 min, the sample was removed from theetchant, rinsed in water, ethanol, and then dried in air. As the etchingrate of Si (100) in 40 wt % KOH at 75° C. is about 50 μm/h, the minimumthickness of SiO₂ can be about 250 nm for an experimentally viablefabrication procedure. In view of this, a 1 μm thick SiO₂ layer wasselected.

Example 6 Characterization of Thermal Actuation

Thermal actuation was characterized with atomic force microscopy (AFM),resistance measurements, and thermal imaging. For characterizationpurposes, samples were used that consisted of the heater coil array andPDMS coating layer, but no tip array. When no power was applied to theheaters, thermal imaging revealed the structure of the coils and leadsas slight differences in temperature (FIG. 12A—top). When 28 mW wasapplied to the top left heater for 1 s, a temperature plume was visible,centered on the selected heater (FIG. 12A—bottom). A maximum temperatureincrease of about 35° C. was observed in this case. The thermalactuation of the PDMS can be directly measured with AFM by scanning incontact mode (Dimension Icon-Bruker) using a contact mode probe(PPP-CONT-NanoWorld AG) in a small (100×100 nm²) region on the PDMSabove the heater. Scans were taken with a resolution of 4096 points and10 lines at 0.1 Hz. The deflection set point was 1 V and the integraland proportional gain were 5 and 10 respectively. At the same time, theheater was driven with a 0.5 Hz square wave at a set power P. The heightrecorded by the AFM was a square wave with damping given by the finiteheating time of the PDMS (FIG. 12B). Each rise and fall of the heightwas fit to the sum of two exponentials and was characterized by a totalamplitude A and a rise time τ defined to be the time required to reach63% (equivalent to the time constant of an exponential function). τ wasfound to only depend on the thickness of the PDMS film and equaled about20 ms for a 40 μm thick PDMS film and 40 ms for a 90 μm thick PDMS film.Both of these times are adequately fast for a molecular patterning. Theamplitude A was found to depend linearly on the applied power P (FIG.12C). The constant of proportionality a increases with smaller heatersand increases with thicker PDMS films. a was found to be between 87nm/mW and 120 nm/mW.

AFM was also used to evaluate the importance of crosstalk between tipsand fatigue with continued use. FIG. 12D shows the amplitude of drivingrecorded at different locations along the surface of the PDMS when theheater at the origin was driven with 28 mW for 50 ms. The red trace wasthe initial measurement and it was apparent that since the amplitude at150 μm was only 20% its peak value, crosstalk between tips will not bean issue. It is worth noting that crosstalk was a considerably largerissue if the power was left on longer, reaching about 40% at 1 s. Byrestricting the on time, it was possible to mitigate crosstalk. Fatiguewas also not an issue as after cycling for 12 hours (23,000 on/offcycles) the amplitude vs. position curve was barely different (FIG. 12Dblack line). This characterization shows that thermal actuation ispowerful and fast enough to perform actuated SPL and that crosstalk andfatigue are not major concerns.

The foregoing describes and exemplifies the invention but is notintended to limit the invention defined by the claims which follow. Allof the methods disclosed and claimed herein can be made and executedwithout undue experimentation in light of the present disclosure. Whilethe materials and methods of this invention have been described in termsof specific embodiments, it will be apparent to those of skill in theart that variations may be applied to the materials and/or methods andin the steps or in the sequence of steps of the methods described hereinwithout departing from the concept, spirit and scope of the invention.More specifically, it will be apparent that certain agents which areboth chemically and physiologically related may be substituted for theagents described herein while the same or similar results would beachieved.

All patents, publications and references cited herein are hereby fullyincorporated by reference. In case of conflict between the presentdisclosure and incorporated patents, publications and references, thepresent disclosure should control.

The following additional considerations apply to the foregoingdiscussion. Throughout this specification, plural instances mayimplement methods, instructions, functions, components, operations, orstructures described as a single instance. Although individual methodsand instructions are illustrated and described as separate operations,one or more of the methods and instructions may be performedconcurrently, and nothing requires that the operations be performed inthe order illustrated. Structures and functionality presented asseparate components in example configurations may be implemented as acombined structure or component. Similarly, structures and functionalitypresented as a single component may be implemented as separatecomponents. These and other variations, modifications, additions, andimprovements fall within the scope of the subject matter herein.

For example, the various component of the system 100 may communicatethrough any combination of a LAN, a MAN, a WAN, a mobile, a wired orwireless network, a private network, or a virtual private network.Moreover, while only one actuation computer is illustrated in FIG. 1 tosimplify and clarify the description, it is understood that any numberof computers or display devices are supported and can be incommunication with the system 100.

Additionally, certain embodiments are described herein as includinglogic or a number of methods, instructions, modules, etc. Methods andmodules may constitute either software modules (e.g., non-transitorycode stored on a tangible machine-readable storage medium) or hardwaremodules. A hardware module is a tangible unit capable of performingcertain operations and may be configured or arranged in a certainmanner. In example embodiments, one or more computer systems (e.g., astandalone, client or server computer system) or one or more hardwaremodules of a computer system (e.g., a processor or a group ofprocessors) may be configured by software (e.g., an application orapplication portion) as a hardware module that operates to performcertain operations as described herein.

In various embodiments, a hardware module may be implementedmechanically or electronically. For example, a hardware module maycomprise dedicated circuitry or logic that is permanently configured(e.g., as a special-purpose processor, such as a field programmable gatearray (FPGA) or an application-specific integrated circuit (ASIC)) toperform certain functions. A hardware module may also compriseprogrammable logic or circuitry (e.g., as encompassed within ageneral-purpose processor or other programmable processor) that istemporarily configured by software to perform certain operations. Itwill be appreciated that the decision to implement a hardware modulemechanically, in dedicated and permanently configured circuitry, or intemporarily configured circuitry (e.g., configured by software) may bedriven by cost and time considerations.

Accordingly, the term hardware should be understood to encompass atangible entity, be that an entity that is physically constructed,permanently configured (e.g., hardwired), or temporarily configured(e.g., programmed) to operate in a certain manner or to perform certainoperations described herein. Considering embodiments in which hardwaremodules are temporarily configured (e.g., programmed), each of thehardware modules need not be configured or instantiated at any oneinstance in time. For example, where the hardware modules comprise ageneral-purpose processor configured using software, the general-purposeprocessor may be configured as respective different hardware modules atdifferent times. Software may accordingly configure a processor, forexample, to constitute a particular hardware module at one instance oftime and to constitute a different hardware module at a differentinstance of time.

Hardware and software modules can provide information to, and receiveinformation from, other hardware and/or software modules. Accordingly,the described hardware modules may be regarded as being communicativelycoupled. Where multiple of such hardware or software modules existcontemporaneously, communications may be achieved through signaltransmission (e.g., over appropriate circuits and buses) that connectthe hardware or software modules. In embodiments in which multiplehardware modules or software are configured or instantiated at differenttimes, communications between such hardware or software modules may beachieved, for example, through the storage and retrieval of informationin memory structures to which the multiple hardware or software moduleshave access. For example, one hardware or software module may perform anoperation and store the output of that operation in a memory device towhich it is communicatively coupled. A further hardware or softwaremodule may then, at a later time, access the memory device to retrieveand process the stored output. Hardware and software modules may alsoinitiate communications with input or output devices, and can operate ona resource (e.g., a collection of information).

The various operations of example functions and methods described hereinmay be performed, at least partially, by one or more processors that aretemporarily configured (e.g., by software) or permanently configured toperform the relevant operations. Whether temporarily or permanentlyconfigured, such processors may constitute processor-implemented modulesthat operate to perform one or more operations or functions. The modulesreferred to herein may, in some example embodiments, compriseprocessor-implemented modules.

Similarly, the methods and instructions described herein may be at leastpartially processor-implemented. For example, at least some of theinstructions of a method may be performed by one or processors orprocessor-implemented hardware modules. The performance of certain ofthe instructions may be distributed among the one or more processors,not only residing within a single machine, but deployed across a numberof machines. In some example embodiments, the processor or processorsmay be located in a single location (e.g., within a laboratoryenvironment, a factory environment or as a server farm), while in otherembodiments the processors may be distributed across a number oflocations.

The one or more processors may also operate to support performance ofthe relevant operations in a “cloud computing” environment or as a“software as a service” (SaaS). For example, at least some of thefunctions may be performed by a group of computers (as examples ofmachines including processors), these operations being accessible via anetwork (e.g., the Internet) and via one or more appropriate interfaces(e.g., application program interfaces (APIs).

The performance of certain of the operations may be distributed amongthe one or more processors, not only residing within a single machine,but deployed across a number of machines. In some example embodiments,the one or more processors or processor-implemented modules may belocated in a single geographic location (e.g., within a lab environment,etc.). In other example embodiments, the one or more processors orprocessor-implemented modules may be distributed across a number ofgeographic locations.

Some portions of this specification are presented in terms of algorithmsor symbolic representations of operations on data and data structuresstored as bits or binary digital signals within a machine memory (e.g.,a computer memory). These algorithms or symbolic representations areexamples of techniques used by those of ordinary skill in the dataprocessing arts to convey the substance of their work to others skilledin the art. As used herein, a “method” or an “instruction” or an“algorithm” or a “routine” is a self-consistent sequence of operationsor similar processing leading to a desired result. In this context,methods, instructions, algorithms, routines and operations involvephysical manipulation of physical quantities. Typically, but notnecessarily, such quantities may take the form of electrical, magnetic,or optical signals capable of being stored, accessed, transferred,combined, compared, or otherwise manipulated by a machine. It isconvenient at times, principally for reasons of common usage, to referto such signals using words such as “data,” “content,” “bits,” “values,”“elements,” “symbols,” “characters,” “terms,” “numbers,” “numerals,” orthe like. These words, however, are merely convenient labels and are tobe associated with appropriate physical quantities.

Unless specifically stated otherwise, discussions herein using wordssuch as “processing,” “computing,” “calculating,” “determining,”“presenting,” “displaying,” or the like may refer to actions orprocesses of a machine (e.g., a computer) that manipulates or transformsdata represented as physical (e.g., electronic, magnetic, or optical)quantities within one or more memories (e.g., volatile memory,non-volatile memory, or a combination thereof), registers, or othermachine components that receive, store, transmit, or displayinformation.

As used herein any reference to “some embodiments” or “one embodiment”or “an embodiment” means that a particular element, feature, structure,or characteristic described in connection with the embodiment isincluded in at least one embodiment. The appearances of the phrase “inone embodiment” in various places in the specification are notnecessarily all referring to the same embodiment.

Some embodiments may be described using the expression “coupled” and“connected” along with their derivatives. For example, some embodimentsmay be described using the term “coupled” to indicate that two or moreelements are in direct physical or electrical contact. The term“coupled,” however, may also mean that two or more elements are not indirect contact with each other, but yet still co-operate or interactwith each other. The embodiments are not limited in this context.

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a function,process, method, article, or apparatus that comprises a list

1.-25. (canceled)
 26. A method of aligning a tip array and pattern ofradiation projected from a projector, comprising: positioning aprojector comprising a digital micromirror device and a macro lens adistance from a tip array, the distance being substantially equal to thefocal length of the macro lens; aligning the digital micromirror device,the macro lens and a beam splitter using an optical breadboard;displaying a first test pattern of radiation from the projector andprojecting the first test pattern onto the tip array, wherein the firsttest pattern has first ratio of L/N, wherein L is the number of mirrorsdisposed on an edge of an illuminated portion of the test pattern and Nis the number of tips disposed on an edge of an illuminated portion ofthe test pattern; observing the projected test pattern projected on aback surface of the tip array; adjusting the position of the digitalmicromirror device to center the first test pattern on the tips disposedin the irradiate portion of the first test pattern; adjusting theposition of the beam splitter until the test pattern is in rough focuson the tip array; adjusting the focal length of the macro lens until thetest pattern is in sharp focus; projecting a second test pattern ofradiation onto the tip array, wherein the second test pattern has asecond ratio of L/N that is smaller than the first ratio of L/N;adjusting the size, orientation, and position of the second test patternsuch that the projected second test pattern substantially matches thetips in the array until one tip of the tip array is in the center ofeach irradiated portion of the second test pattern.
 27. The method ofclaim 26, wherein the first test pattern is in the form of acheckerboard and sized such that at least a 5×5 array of tips isdisposed in a single irradiated square of the checkerboard.
 28. Themethod of claim 26, comprising observing the projected test patternusing a camera focused on the back surface of the tip array.
 29. Themethod of claim 26, wherein the second test pattern is in the form of acheckerboard.
 30. A tip array, comprising: an elastomeric tip substratelayer comprising a first surface and an oppositely disposed secondsurface, the tip substrate layer being formed from an elastomericmaterial; a plurality of tips fixed to the first surface, the tips eachcomprising a tip end disposed opposite the first surface, the tipshaving a radius of curvature of less than about 1 micron; and an arrayof heaters disposed on the second surface of the tip substrate layer andconfigured such that when the tip substrate layer is heated by a heater,a tip disposed in a location of a heated portion of tip substrate layeris lowered relative to a tip disposed in a location of an unheatedportion of the tip substrate layer.
 31. The tip array of claim 30,wherein the tips are formed of an at least translucent material, the tiparray further comprising a blocking layer coated on the tips and thefirst surface; and a plurality of apertures defined in the blockinglayer exposing the tip ends of the plurality of tips.
 32. The tip arrayof claim 30, wherein the tips are comprise an elastomer.
 33. The tiparray of claim 30, wherein the elastomer of the one or more tips and/orthe elastomeric tip substrate layer comprises a polymer, a cross-linkedpolymer, or a polymer gel.
 34. The tip array of claim 30, wherein theelastomer of the one or more tips and/or the elastomeric tip substratelayer comprises polydimethylsiloxane (PDMS).
 35. The tip array of claim30, wherein the tips comprise a metal, a metalloid (optionally silicon),a semi-conducting material, or a combination thereof.
 36. The tip arrayof claim 30, further comprising a rigid support to which the tipsubstrate layer is attached, the heaters being disposed between therigid support and the tip substrate layer.
 37. The tip array of claim36, wherein the rigid support is a glass slide.
 38. The tip array ofclaim 30, wherein one or more of the tip substrate layer, the rigidsupport, and the tips are translucent.
 39. The tip array of claim 30,wherein the heaters are electrically activated heaters.
 40. The tiparray of claim 39, wherein the heaters are formed of indium tin oxide,graphene, poly(3,4-ethylenedioxythiophene) (PEDOT), gold, copper,platinum, and combinations thereof.
 41. The tip array of claim 30,wherein the heaters are photoconductive heaters.
 42. The tip array ofclaim 41, wherein the photoconductive heaters comprise amorphoushydrogenated silicon, zinc oxide, cadmium selenide, or combinationsthereof.
 43. The tip array of claim 41, further comprising at least onespatial light modulator disposed on at least one of the photoconductiveheaters.
 44. The tip array of claim 43, wherein the at least one spatiallight modulator is dynamically controllable.
 45. The tip array of claim41, further comprising an array of spatial light modulators disposed onthe photoconductive heaters.
 46. The tip array of claim 30, wherein thetip array comprises electrically activated heaters and photoconductiveheaters.
 47. The tip array of claim 30, wherein the heaters are at leasttranslucent.
 48. The tip array of claim 47, wherein the heaters aretransparent.
 49. The tip array of claim 30, wherein each heater of thearray of heaters is aligned with one tip of the tip array.
 50. The tiparray of claim 30, wherein each the heater is disposed in a region ofthe tip substrate layer corresponding to a heating zone comprising oneor more tips, wherein upon activation of the heater the one or more tipsin the heating zone are lowered relative to a tip disposed outside theheating zone.
 51. The tip array of claim 30, further comprising agraphene film coated on at least the tips of the tip array.
 52. A methodfor selectively actuating one or more tips of the tip array of claim 30,comprising selectively activating one or more heaters to heat a portionof the elastomeric tip substrate layer to selectively lower one or moretips disposed in the location of the heated portion of the tip substratelayer relative to a tip disposed in an unheated portion of the tipsubstrate layer.
 53. The method of claim 52, further comprisingcontacting the substrate with the tip array before selectivelyactivating the one or more heaters, wherein selecting activating the oneor more heaters selectively heats a portion of the tip substrate layerto selectively lowers one or more tips into closer contact to printlarger feature sizes as compared to feature sizes printed by tipsdisposed in an unheated portion of the tip substrate layer.
 54. Themethod of claim 52 or 53, wherein each heater is disposed in a heatingzone comprising one or more tips and selectively activating the heaterin the heating zone selectively lowers the one or more tips in theheating zone relative to a tip disposed outside the heating zone. 55.The method of claim 52, wherein each heater is aligned with a single tipand selectively activating the heater selectively lowers only the tipwhich aligned with the activated heater.
 56. A method of selectivelyapplying a patterning composition to one or more tips of the tips arrayof claim 30, comprising: disposing the tip array adjacent to, but not incontact with one or more patterning composition sources; and selectivelyactivating one or more heaters to heating a portion of the elastomerictip substrate layer to selectively lower one or more tips disposed inthe location of the heated portion of the elastomeric tip substratelayer into contact with the one or more patterning composition sources.57. A method of selectively applying a patterning composition to one ormore tips of the tips array of claim 30, comprising: selectivelyactivating one or more heaters to heating a portion of the elastomerictip substrate layer to selectively lower one or more tips disposed inthe location of the heated portion of the elastomeric tip substratelayer; disposing the tip array adjacent to one or more patterningcomposition sources such that the selectively lowered one or more tipsare placed into contact with the one or more patterning compositionsources.
 58. A method of selectively applying two different patterningcompositions to the tips of the tip array of 30, comprising: disposingthe tip array adjacent to, but not in contact with a first patterningcomposition source; selectively heating a portion of the elastomeric tipsubstrate layer to selectively lower a first subset of one or more tipsdisposed in the location of the heated portion of the elastomeric tipsubstrate layer into contact with the first patterning compositionsource to apply the first patterning composition to the first subset ofone or more tips; disposing the tip array adjacent to, but not incontact with a second patterning composition source comprising a secondpatterning composition; selectively heating a portion of the elastomerictip substrate layer to selectively lower a second subset of one or moretips disposed in the location of the heated portion of the elastomerictip substrate layer into contact with the second patterning compositionsource to apply the second patterning composition to the second subsetof one or more tips.
 59. The method of claim 52, wherein the heaters arephotoconductive heaters and selectively heating a portion of theelastomeric tip substrate layer comprises selectively irradiating one ormore of the photoconductive heaters.
 60. The method of claim 59,comprising activating the one or more heaters by irradiating the heaterswith a pattern of radiation, the pattern of radiation corresponding tothe one or more heaters to be activated.
 61. The method of claim 52,wherein the heaters are photoconductive heaters, the tip array comprisesan array of spatial light modulators disposed on the photoconductiveheaters, and selectively heating a portion of the elastomeric tipsubstrate layer comprises irradiating the tip substrate layer andselectively actuating the spatial light modulators to expose one or moreof the photoconductive heaters to the irradiation.
 62. The method ofclaim 52, wherein the heaters comprise a first subset of photoconductiveheaters adapted to activate in response to a first radiation, and asecond subset of photoconductive heaters adapted to activate in responseto a second radiation, the first and second radiations having differentwavelengths, and selectively activating one or more of the first subsetof photoconductive heaters comprises irradiating one or more of theheaters with the first radiation and selectively activating one or moreof the second subset of photoconductive heaters comprises irradiatingone or more of the heaters with the second radiation.
 63. The method ofclaim 62, wherein selectively actuating one or more heaters comprisesirradiating all the heaters with the first radiation, wherein only thefirst subset of photoconductive heaters are activated to selectivelylower one or more tips of the tip array.
 64. The method of claim 62,wherein selectively actuating one or more heaters comprises irradiatingall the heaters with the second radiation, wherein only the secondsubset of photoconductive heaters are activated to selectively lower oneor more tips of the tip array.
 65. The method of claim 52, wherein theheaters are electric heaters and selectively activating one or moreheaters comprises supplying a voltage to the one or more heaters.66.-77. (canceled)